UNIVERSITY  OF  CALIFORNIA. 


Class 


HOW    CROPS    GROW. 

A   TREATISE    ON   THE 

CHEMICAL    COMPOSITION,    STRUCTURE 
AND    LIFE    OF    THE    PLANT, 

FOR 

ALL    STUDENTS    OF    AGRICULTURE. 

WTTH     NUMEROUS    ILLUSTRATIONS    AND    TABLES     OP    ANALYSES. 


BY 

SAMUEL  W.  JOHNSON,  M.  A., 

PROFESSOR  OF   ANALYTICAL,  AND   AGRICULTURAL  CHKMI8TR1    IX  THE 

soito">i,  or  Y.VLB  COLLEGE;  CUEMIST  TO   THE  CONNEC 
TICUT    8TATK    AGRICULTURAL    SOCIETY;    MEMBEB,    OK    TOB 
NATIONAL,  ACADEMY  OF  SCIENCES. 


NEW    YORK: 

0.   JUDD    CO.,   DAVID    W.   JUDD,   PBES'T, 

751    BROADWAY. 


Entered  according  to  Act  of  Congress,  in  the  yeai  1869,  by 
ORANGE  JUDD  &  CO., 


kt  the  Clerk's  Office  of  the  District  Court  of  the  United  States  for  the 
Southern  District  of  New-  York. 


LOVEJOY,  SON  &  Co.. 

ELECTHOTYPERS  &  STEREOTYPES*, 

15  Vandewater  Street,  N.   Y. 


OF  THE  \ 

(    UNIVERSITY  | 

OF 

ii^QP^ 


PREFACE. 


For  the  last  twelve  years  it  has  been  the  duty  of  the 
writer  to  pronounce  a  course  of  lectures  annually  upon 
Agricultural  Chemistry  and  Physiology  to  a  class  in  the 
Scientific  School  of  Yale  College.  This  volume  is  a  result 
of  studies  undertaken  in  preparing  these  lectures.  It  is 
intended  to  be  one  of  a  series  that  shall  cover  the  whole 
subject  of  the  applications  of  Chemical  and  Physiological 
Science  to  Agriculture,  and  is  offered  to  the  public  in  the 
hope  that  it  will  supply  a  deficiency  that  has  long  existed 
in  English  literature. 

The  prcgre»3  of  these  branches  of  science  during  recent 
years  has  been  very  great.  Thanks  to  the  activity  of 
numerous  English,  French,  and  especially  German  inves 
tigators,  Agricultural  Chemistry  has  ceased  to  be  the 
monopoly  of  speculative  minds,  and  is  well  based  on  a 
foundation  of  hard  work  in  the  study  of  facts  and  first 
principles.  Vegetable  Physiology  has  likewise  made  re 
markable  advances,  has  disencumbered  itself  of  many 
useless  accumulations,  and  has  achieved  much  that  is  of 
direct  bearing  on  the  art  of  cultivation. 

The  author  has  endeavored  in  this  work  to  lay  out  a 
groundwork  of  facts  sufficiently  complete  to  reflect  a  true 
and  well-proportioned  image  of  the  nature  and  needs  of 
the  plant,  and  to  serve  the  student  of  agriculture  for 
thoroughly  preparing  himself  to  comprehend  the  whole 


rv  now  CROPS  GHOW. 

subject  of  vegetable  nutrition,  and  to  estimate  accurately 
]  -ow  and  to  what  extent  the  crop  depends  upon  the  at- 
•here  on  the  one  hand,  and  the  soil  on  the  other,  for 
the  elements  of  its  growth. 

It  has  been  sought  to  present  the  subject  inductively, 
to  collate  and  compare,  as  for  as  possible,  all  the  facts,  and 
so  to  describe  and  discuss  the  methods  of  investigation 
that  the  conclusions  given  shall  not  rest  on  any  individual 
authority,  but  that  the  student  may  be  able  to  judge  him 
self  of  their  validity  and  importance.  In  many  cnses  ful 
ness  of  detail  has  been  employed,  from  a  conviction  that 
an  acquaintance  with  the  sources  of  information,  and  with 
the  processes  by  which  a  problem  is  attacked  and  truth  ar 
rived  at,  is  a  necessary  part  of  the  education  of  those  who 
are  hereafter  to  be  of  service  in  the  advancement  of  agri 
culture.  The  Agricultural  Schools  that  are  coming  into 
operation  should  do  more  than  instruct  in  the  general  re 
sults  of  Agricultural  Science.  They  should  teach  the 
subject  so  thoroughly  that  the  learner  may  comprehend 
at  once  the  deficiencies  and  the  possibilities  of  our  knowl 
edge.  Thus  we  may  hope  that  a  company  of  capable  in 
vestigators  may  be  raised  up,  from  whose  efforts  the 
science  and  the  art  may  receive  new  and  continual  im 
pulses. 

In  preparing  the  ensuing  pages  the  writer  has  kept  his  eye 
Btea  lily  iixed  upon  the  practical  aspects  of  the  subject.  A 
multitude  of  interesting  details  have  be  >n  omitted  for  the 
sake  of  comprising  within  a  reasonable  space  that  informa 
tion  which  may  most  immediately  serve  the  agriculturist. 
It  must  not,  however,  be  forgotten,  that  a  valuable  principle 
is  often  arrived  at  from  the  study  of  facts,  which,  consid 
ered  singly,  have  no  visible  connection  with  a  practical 
result.  Statements  are  made  which  may  appear  far  more 
curious  than  useful,  and  that  have,  at  present,  a  simply 
speculative  interest,  no  mode  being  apparent  by  which  the 
farmer  can  increase  his  crops  or  diminish  his  labors  by  help 


PREFACE.  V 

of  his  acquaintance  with  them.  Such  facts  are  not,  how 
ever,  for  this  reason  to  be  ignored  or  refused  a  place  in  our 
treatise,  nor  do  they  render  our  book  less  practical  or  less 
valuable.  It  is  just  such  curious  and  seemingly  useless 
facts  that  are  often  the  seeds  of  vast  advances  in  industry 
and  arts. 

For  those  who  have  not  enjoyed  the  advantages  of  the 
schools,  the  author  has  sought  to  unfold  his  subjects  by 
such  regular  and  simple  steps,  that  any  one  may  easily 
master  them.  It  has  also  been  attempted  to  adapt  the 
work  in  form  and  contents  to  the  wants  of  the  class-room 
by  a  strictly  systematic  arrangement  of  topics,  and  by  di 
vision  of  the  matter  into  convenient  paragraphs. 

To  aid  the  student  who  has  access  to  a  chemical  labor 
atory  and  desires  to  make  himself  practically  familiar 
with  the  elements  and  compounds  that  exist  in  plants,  a 
number  of  simple  experiments  are  described  somewhat  in 
detail.  The  repetition  of  these  will  be  found  extremely 
useful  by  giving  the  learner  an  opportunity  of  sharpening 
his  perceptive  powers,  as  well  as  of  deepening  the  impres 
sions  of  study. 

The  author  has  endeavored  to  make  this  volume  com 
plete  in  itself,  and  for  that  purpose  has  introduced  a  short 
section  on  The  Food  of  the  Plant.  In  the  succeeding  vol 
ume,  which  is  nearly  ready  for  the  printer,  to  be  entitled 
"How  Crops  Feed,"  this  subject  will  be  amplified  in  all 
its  details,  and  the  atmosphere  and  the  soil  will  be  fully 
discussed  in  their  manifold  Relations  to  the  Plant.  A 
third  volume,  it  is  hoped,  will  be  prepared  at  an  early  day 
upon  Cultivation;  or,  the  Improvement  of  the  Soil  and  tho 
Crop  by  Tillage  and  Manures.  Lastly,  if  time  and 
strength  do  not  fail,  a  fourth  work  on  Stock  Feeding  and 
Dairy  Produce,  considered  from  the  point  of  view  of 
chemical  and  physiological  science,  may  finish  the  series. 

It  is  a  source  of  deep  and  continual  regret  to  the  write! 
that  his  efforts  in  the  field  of  agriculture  have  been  mostly 


71  HOW    CROPS    GROW. 

confined  to  editing  and  communicating  the  results  of  the 
labors  of  others. 

He  will  not  call  it  a  misfortune  that  other  duties  of  life 
and  of  his  professional  position  have  fully  employed  his 
time  and  his  energies,  but  the  fact  is  his  apology  for  be 
ing  a  middleman  and  not  a  producer  of  the  priceless  com 
modities  of  science.  He  hopes  yet  that  circumstances 
may  put  it  in  liis  power  to  give  his  undivided  attention  to 
the  experimental  solution  of  numerous  problems  which 
now  perplex  both  the  philosopher  and  the  farmer ;  nnd 
he  would  earnestly  invite  young  men  reared  in  familiarity 
with  the  occupations  of  the  farm,  who  are  conscious  of 
the  power  of  investigation,  to  enter  the  fields  of  Agricul 
tural  Science,  nOw  white  with  a  harvest  for  which  the 
are  all  too  few. 


ACKNOWLEDGMENTS. 


The  author  would  express  his  thanks  to  his  friend  Dr. 
Peter  Collier,  Professor  of  Chemistry  in  the  University 
of  Vermont,  for  a  large  share  of  the  calculations  and  re 
ductions  required  for  the  Tables  pp.  150-6. 

Of  the  illustrations,  fig's  3,  4,  5,  7,  47,  63,  and  64,  were 
drawn  by  Mr.  Lockwood  Sanford,  the  engraver.  For  oth 
ers,  acknowledgments  are  due  to  the  following  authors, 
from  whose  works  they  have  been  borrowed,  viz. : 

SOHLEIDEN. — Fig's  10,  13,  17,  19,  30,  48,  49,  and  50, 
Physiologic  der  Pflanzen  und  Thicre. 

SACHS. — Fig's  56  and  65,  Silztmgsberichte  der  Wiener 
Akademie,  XXXVII,  1859,  and  fig's  22,  38,  40,  41,  42, 
43,  59,  66,  69,  70,  and  71,  Experimental-Physiologie  der 
Pflanzen. 

PAYEN. — Fig's*  11,  12,  and  23,  Precis  de  Chimie  Tndut- 
trielle. 

DUCHARTRE. — Fig's  60  and  61,  Elements  de  Botanique. 

KiiHN.  —  Fig's  18,  21a,  29,  and  34,  Ernahrung  des 
Rindviehes. 

HARTIG. — Fig's  20,  21b,  32,  Entwickelungsgeschichte 
des  Pflanzenkeims. 

UNGER. — Fig.  26,  Sitzungsberichte  der  Wiener  Akade- 
mie,  XLIII,  and  fig.  55,  Anat.  u.  Phys.  der  Pflanzen. 

SCHACHT. — Fig's  33,  37,  44,  Anatomic  der  Gewmchse, 
fig's  51,  53,  54,  and  62,  Der  Bourn,  and  fig's  52,  57,  and 
58,  Die  IZartoffel  und  ihre  Krankheiten. 

HENFREY. — Fig's  36  and  39,  Jour.  Hoy.  Ag.  Soe,  of 
England,  Vol.  XIX,  pp.  483  and  484. 
7 


I: 


TABLE    OF    CONTENTS. 

INTRODUCTION 17 

DIVISION  I.— CHEMICAL  COMPOSITION  OF  THE  PLANT. 

CHAP.  I.— THE  VOLATILE  PAKT  OP  PLANTS .  38 

§  1.  Distinctions*  and  Definitions 28 

§  2.  Elements  of  the  Volatile  Part  of  Plants 31 

Carbon,  Hydrogen,  Oxygen,  Nitrogen,  Sulphur,  Phosphor 
us,  Ultimate  Composition  of  Organic  Matter -1: 

3.  Chemical  Affinity 

4.  Vegetable  Organic  Compounds  or  Proximate  Elements 

1.  Water • 

2.  Cellulose  Group ;V. 

8.  Pectose        " SI 

4.  Vegetable  Acids 85 

5.  Fats Ml 

6.  Albuminoids !H 

Appendix,  Chlorophyll,  etc 10!) 

CHAP,  n.— TUE  ASH  OF  PLANTS Ill 

§  1.  Ingredients  of  the  Ash Ill 

Non-metallic  Elements 112 

Carbon         and  its  Compounds 113 

Sulphur          114 

Phosphorus"     "  "  117 

Silicon  "      "  "  11!) 

Metallic  Elements 123 

Potassium  and  its  Compounds 19-1 

Sodium         "    "          "  124 

Calcium         "    "  "  125 

Magnesium  and  its  Compounds 126 

Iron  127 

Manganese     "    "          "  128 

Salts 129 

Carbonates 130 

Sulphates 132 

Phosphates 133 

Chlorides 135 

Nitrates 136 

§  2.  Quantity,  Distribution,  and  Variations  of  the  Ash 138 

Table  of  Proportions  of  Ash  in  Vegetable  Matter 139 

\  3.  Special  Composition  of  the  Ash  of  Agricultural  Plants 147 

1.  Constant  Ingredients \ 148 

2.  Uniform  composition  of  normal  special's  of  given  plant.148 
Table  of  Ash-analyses 150 

3.  Composition  of  Different  parts  of  Plant 157 

4.  Like  composition  of  similar  plants 159 

5.  Variability  of  ash  of  same  species ISO 

6.  What  is  normal  composition  of  the  ash  of  a  plant  ? 103 

7.  To  what  extent  is  each  ash-ingredient  essential"  or  acci 

dental 166 

Water-culture 167 

ntial  ash-ingredients 172 

Is  Soda  Essential  to  Agricultural  Plants  ? 172 

Oxide  of  Iron  indispensable 178 

Oxide  of  Manganese  unessential 179 

Is  chlorine  indispensable  ? 180 

Silica  is  not  essential 183 

Ash-ingredients  taken  up  in  excess ....     1^7 

Disposition  of  superfluous  matters l!S9 

State  of  Ash-Ingredient!  in  plant lit.] 

§  4.  Functions  of  the  Ash-ingredients 1% 

CHAP.  III. — §  1.  Quantitative  .Relations  among  the  Ingredients  of  Plants 201 

§  2.  Comno-ition  of  the  plant  in  KIUT^S:  ve  stages  of  growth 203 

Composition  and  (Jrowth  of  tin-  Oat  Plant 2iM 

DIVISION  II  -TliK  ST1U CTUIi:  OK  THK  PLANT  AND   OFFICES  OF 
ITS  OKI  JANS. 

CHAP.  I.— GENERALITIES 22(1 

Organ itm,  Organs 88? 

8 


TABLE    OF    CONTENTS.  IX 

CHAP,  n.-  -PRIMARY  ELEMENTS  OF  ORGANIC  STRUCTURE 223 

1 1.  The  Vegetable  Cell .223 

$2.  Vegetable  Tissues 233 

^AP.  HI. — VEGETATIVE  ORGANS 234 

§  1.  The  Root 234 

Spongioles,  Root  Cap 23? 

Offices  of  Root 2:5:' 

Delicacy  of  Structure..) 23!« 

Apparent  Search  for  Food 211 

Root-hairs 243 

Contact  of  Roots  with  Soil 2 1  j 

Absorption  by  Root.. 218 

Soil  Roots,  Water  Roots,  Air  Roots 'iVi 

Excretions 253 

f  2.  The  Stem 200 

Buds 201 

Layers,  Tillering 204 

Root-Stocks 20.1 

Tubers 200 

Structure  of  the  Stem 207 

Endogenous  Plants 20-s 

Exogenous        "•       273 

Sieve-cells 2SO 

§3.  Leaves 283 

Leaf  Pores 285 

Exhalation  of  Water  Vapor 287 

Offices  of  Foliage 290 

CHAP.  IV.—  REPRODUCTIVE  ORGANS 291 

§  1.  The  Flower 291 

Fertilization 294 

Hybridizing 295 

Darwin's  Hypothesis 293 

§2.  Fruit 3M 

Seed 302 

Endosperm 302 

Embryo 302 

§  3.  Vitality  of  seeds  and  their  influence  on  the  Plants  they  produce.305 

Duration  of  Vitality 305 

Use  of  old.  unripe  and  light  fceeds 307 

Church's  Experiments  on  Seed  Wheat 308 

DIVISION  III.— LIFE  OF  THE  PLANT. 

CHAP.  I. — GERMINATION 310 

§  1.  Introductory 310 

§  2.  Phenomena  of  Germination 311 

§  3.  Conditions  of  Germination 312 

Proper  Depth  of  Sowing 310 

§  4.  Chemical  Physiology  of  Germination 318 

Chemistry  of  Malt 319 

CHAP.  II.—  §  1.  Food  of  the  Plant  when  independent  of  the  Seed 327 

§  2.  The  Juices  of  the  Plant.    Their  Nature  and  Movements 330 

Flow  of  Sap 331 

Bleeding 332 

Composition  of  Sap .337 

Kinds  of  Sap 338 

Motion  of  Nutrient  Matters 310 

§3.  Causes  of  Motion  of  the  Juices 340 

Porosity  of  Tissues 340 

Imbibition 310 

Capillary  Attraction ;> !'i 

^iquid  Diffusion 3>1 

Osmose  or  Membrane  Diffusion :jf>l 

Root  Action  :j\\  i 

Selective  Power  of  Plant 302 

|  4.  Mechanical  EtlVcts  of  Osmose; 3(58 

§  5.  Direction  of  Vegetable  Growth .370 

APPENDIX.— TABLES. 
TABLE  I. — Composition  of  the  Ash  of  Agrlcaifl  Plants  aiid  Products.  Average 9. 378 


HOW   CROPS   GROW. 


TABLE  II. —Composition  of  Fresh  or  Air-dry  AgricultM  Products  in  1,000  parts. .381 

TABLE  III.— Proximate  Composition  of  Agricultural  Plant?  and  Products 385 

TABLE  IV.— Detailed  Analyses  of  Bread  Grains :>M 

TABLE  V.— Detailed  Analyses  of  Potatoes 389 

TABLE  VI.— Detailed  Analyses  of  Sugar  Beets . .  38!) 

TABLE  VII.— Composition  of  Fruits 390 

TABLE  VIII.— Fruits  arranged  in  the  Order  of  their  Content  of  Sugar 393 

TABLE  IX.— Fruits  arranged  in  the  Ord".r  of  their  Content  of  Free  Acid 393 

TABLE  X. — Fruits  arranged  according  to  proportions  between  Acid,  Sugar,  etc..S9-3 
TABLE  XI. — Fruits  arranged  according  to  the  proportions  between  Water, 

Soluble  Matters,  etc 394 

TABLE  XIL— Proportion  of  Oil  in  Seeds 394 


INDEX. 


Absorption  by  the  root 239,  250,  251 

Access  of  air  to  interior  of  Plant. .  .288 

Acids,  Definition  of 86 

"     Testfor 87 

Acid  elements 113 

Adhesion 26,  349 

Agriculture,  Art  of 17 

Agricultural  products,  Composition 

ill  1,000  parts 381 

Agricultural  Science,  Scope  of. 24 

"         Experiment-Stations  of 

Germany 24 

Air-passages  in  plant 289 

Air-roots 252 

Akene 301 

Albumin 96 

Albuminoids,  Characters  and  com 
position 94 

Albuminoids  in  animal  nutrition...  10-1 

"  Diffusion  of. 364 

"  in  oat-plant 211,215 

Mutual  relations  of. .  .103 
"           Proportion  of,  in  vege 
table  products 109, 

Alburnum 282 

Alcohol  from  saw-dust 75 

Aleurone 105 

Algae 177, 223 

Alkali-earths 125 

"    Function  of 11)7 

"    Metals 125 

Alkali-metals 123 

Alkalies 86,  124 

"     Testfor 87 

"     Function  of 197 

Alkaloids 110 

Alum,  decomposed  by  dift'usion. ..  364 

Alumina 129 

Aluminum 129 

Ammonia,  Carbonate 49 

•k        in  plants 108 

Salts  of 1!57 

"     in  plant 137 

Amyloids 55 

"        Transformation  of. ..    7S 

Anhydrous  phosphoric  acid. ..   — 117 

silicic  acid r.'ii 

•'         sulphuri:  acid 1 1 5 

Anther and 

Apatite !'•'*> 

Apple  Cellbof 223 


Arabic  acid 70 

Arabia 70 

Arendt,  Estimation  of  sulphur  and 

sulphuric  acid ]  95 

Arendt,  Study  of  oat-plant 204 

"      Analysis  of  oat-plant 141 

Argol 88 

Arrowroot (;:} 

Arsenic  in  plants 123,  196 

Art  and  Science 17 

Artificial  fecundation 

Ash-Ingredients 112,  138 

Excess  of. 187 

"         how  dis 
posed  of. 189 

Ash-Ingredients,  Function    of,    in 

plant 196 

Ash-Ingredients,  The  indispensable. 146 
"        State  of,  in  plant. . .  193 

Ash  of  plants 30, 11J 

"    Analyses,  Tables  of.150,-1 
"        "    Composition    of,  nor 
mal 163 

Ash  of  plants,  Composition  of,  va 
riations  in IB7,  163 

Ash  of  oat-crop 212,  216 

"    Proportions  of,  Tables 139,  145 

"    variations  in...  143 

Asparagus,  Ash-analyses 176 

Assimilation 325 

Atmosphere,  Offices  of. 3-J:l 

Atoms , 47 

Atomic  weight 47,  48 

Avenin 101 

Azote :;',! 

Bark 269,  275 

"  Ash  of. IN) 

Barley,  Ash-analyses.  .150,  153,  160,  378 

"      Proximate  analyses 387 

detailed.  38H 

41      Root-cap  of- 23ti 

"      Root-hairs  of 2-14 

Barley-Sugar. 73 

Baryta  in  plant! r.ui 

i',n-rs.  Definition  of 80 

Bassorin 71 

BasMvlls 270,  •„.>;.-> 

a;;:j 

Bay  berry  tallow 91 

Bean.  A>li-;inalyses...     ...152,  154,  37tf 

Proximate  analysis . ..3tff 


Bean,  Leaf,  Section  of 285 

"     Seed 304 

N  Beeswax 91 

Nieet  sugar 73 

Berry 301 

Bicarbonate  of  potash 130 

Bicarbonate  of  soda 131 

Biennial  plants 251 

Bitartrate  of  potash  88 

Bleeding  of  vine 250,  332 

Blight 223 

Blood-fibrin 98 

Boue-black 32 

Bons>  -phosphate 135 

Bread  grains,  Detailed  analyses...  388 
Bretschneider,  Study  of  oat-plant. . .  204 

Bromine 119 

Brucite 127 

Buckwheat,  Ash-analyses.... 152,  153 

163,  378 

Buckwheat,  Proximate  analysis  —  387 
"                  "              "        de 
tailed 388 

Buds,  Structure  of. 261 

"    Development  under  pressure. 368 

Bulbs.   267 

Butyrin 90 

Cabbage,  Section  of  stem,  fig 56 

Cactus  Mnilis,  Lime  salt  in 191 

Caesium 125 

'•        Action  in  oat 196 

Caffcin Ill 

Catfeotanic  acid  110 

Calcium ...125 

Callous 342 

Calyx 292 

Cambium 271,  272,  276,  280 

Cane  sugar 72 

Capillary  attraction 349 

Caramel 73 

Carbon,  Properties  of 31- 

14      In  ash 113 

Carbonates 130 

Carbonate  of  lime 131 

ki  potash 130 

"       "soda 131 

Carbonic  acid 113 

"  as  food  of  plant 328 

"  in  ash-analyses 149 

Carbonization 32 

Carrot,  Ash-analyses 155,  156,  377 

Casein 100 

Cassava 64 

Caiderpa  pivlifera,  fig 230 

Causes  of  directive  power 371 

"    "    motion  of  juices 346 

Caustic  potash 124 

"       soda 125 

Cauto  tree 183 

Cell-contents 228 

"  membrane,  Thickening  of  ....  227 

"  multiplication 231 

"  Structure  of. 224 

Cells,  Forms  of. 226 

"      Sizeof 230 

Cellular  plants 223 

"      tissue 233 

Cellulose.  ..  56 


Cellulose,  Composition Sfl 

Estimation 60 

"        Group 55 

"        Test  for 59 

"        Quantity  of,  in  plants 62 

Cerasin . .     71 

Cereals,  Ash-analyses  of..  .150,  JTT8,  379 

Chaff 294 

kk    Ash  of 373 

Chemical  affinity 46 

"             "       overcome    by   os 
mose  364 

Chemical  combination 46 

"        decomposition 46 

Chemistry 2(5 

Cherry  gum 71 

Chlorhydric  acid 118 

Chlorides 118,  135 

Chloride  of  ammonium,  decompos 
ed  by  plant 171 

Chloride  of  Magnesium 118 

"        "    Potassium 135 

"        "    Sodium 136 

Chlorine 118 

"      essential  to  crops  ? 180,  183 

"      function  in  plant 15'9 

"      in  strand  plants 1*3 

Chlorophyll 109,  285 

"         requires  iron 200 

Church,  on  specific  gravity  of  seeds.308 

Circulation  of  sap 330 

Citric  acid 83 

Citrates 136 

Classes 298 

Classification 2»8 

Clover,  Ash  of. 37t' 

"      soluble  and  insoluble  ash-in 
gredients 194 

Clover,  washed  by  rain 190 

Coagulation 96 

Cochineal  tincture,  test  for  acids  and 

alkalies 87 

Colloids 352 

Combustion 35 

Common  Salt 136 

Composite  plants 300 

Concentration  of  plant-food 171 

Concretions  in  plant 190 

Coniferous  plants 3UO 

Copper  in  plants 129,  196 

Cork 276,  2^7 

Corn-starch 63 

Corolla 292 

Cotton,  ash-analyses 156 

"      fiber,  fig 56,  227 

"      seed  cake,  Analysis  of.. 378,  382 

Cotyledon 268,303 

Crops,  composition  in  1,000  parts... 3S1 

Coniferous  plants 300,  3D4 

Crude  cellulose 60 

Cryptogams.... 223,  299 

Crystalloid  aleuroue 107 

Crystalloids 352 

Crystals  in  plant 190,  192 

Cubic  centimeter 58 

Culms 262 

Cyanides 114 

Cyanogen 114 


XII 


HOW   CROPS    GEOW. 


Cyanophyll  .................   .......  110 

Darwin  on  insect-fertilization  ......  295 

44      Hypothesis  of.  .............  298 

Decimal  system  of  weights  .........  58 

Deflagration  .......................  136 

Definite  Proportions,  Law  of  ......  47 

Deliquescent  ........  .  .............  135 

Density  of  seeds  ...................  308 

Depth  of  sowing  ...................  316 

Dextrin  .............................  69 

Diastase  ............................  321 

Dicalcic  phosphate  ................  134 

Dicotyledonous  seeds  ..............  303 

Diffusion  of  liquids  ................  351 

Diffusion-rates  ......................  352 

Dioecious  plants  ....................  21)4 

Direction  of  growth  ...............  370 

Disodic  phosphate  ................  134 

Double  flowers  ....................  293 

Drains  stopped  by  roots  ............  253 

Drupe  .............................  300 

Dry  weather,  Effect  of,  on  plants.  .  .144 
Ducts  .........................  234,272 

Dundonald's  treatise  on  Ag.  Chem 
istry  ...........................  20 

Elements  of  Matter  ...............  25 

Elm  roots  ..........................  254 

Embryo  ...........................  302 

Enmlsin  ............................  101 

Endogens  .........................  238 

Endogenous  plants  ............  268,  303 

Enclosmose  ........................  355 

Endosperm  ........................  302 

Epidermis..  .......................  269 

'     "        of  leaf.  ..............  285,287 

Equisetum  .........................  184 

Equivalent  replacement  of  bases.  ..201 
Eremacausis  .......................    37 

Estimation  of  Albuminoids  ........  108 

Celluloso  ............  60 

Fat  ..................  94 

Starch  ...........  66,76 

Sugar  ...............  76 

Water  ...............  54 

Etherial  oils  ......................     90 

Excretion  of  mineral  matters  from 
leaves  ........................  192 

Excretions  from  roots.   .  .  .........  25« 

Exhalation  of  water  from  foliage 

..........................  287,  332 

Exogenous  plants  .........  237,  273,  303 

Exogens  ..........................  237 

Bxosmose  ........................  355 

Experiment-Stations  of  Germany...  24 
Extension  of  roots  .................  240 

Extractive  Matters  ..............    (..890 

Exudation  of  ash-ingredients  ......  !>'.» 

Eyes  of  potato  ...................  237 

Families  ...........................  X".H 

Fatty  acids  .........................  '.1:5 

Fats  .............................  89 

41  converted  into  starch  ..........  318 

Fat  in  oat  crop  .................  211,  215 

44  Proportions    of,    in   Vegetable 
Products  ...............  .  .....  in 


l-Vrtilizutioii  .................  .....  2'.U 

Vibur    .  ..  00 


Fiber  in  oat  crop 210,  214 

Fibrin 98 

Field-beet,  ash-analyses.  ...155, 176.  37? 

44      '4     prox.    44        387 

Flax  fiber,  fig 56,  227 

Flesh  fibrin 99 

Fleshy  roots 251 

Flower 291 

Flow  of  sap 331 

Fluorine  in  plants 119,  195 

Fodder  plants,  Ash  of ...  :7rt 

Foliage,  Offices  of. 2M 

44        white  in  absence  of  iron.  .19!) 

Food  of  Plant JW7 

Force 25 

Forces 26 

Formative  layer . .  22  4 

Formulas,  Chemical 50 

Fructification 294 

Fructose 73 

Fruit 300 

Fruits.  Ash  of. ..379 

44      Composition  of. 390 

Fruit  sugar 73 

Fuchsia,  fig.  of  flower 292 

Fungi 223 

C.i;isv's.  how  distributed  throughout 

the  plant 365 

Gallicacid 110 

Gallotannic  acid 110 

Gelatinous  Silica 122, 123 

Genus;   Genera 298 

Germ 302 

Germination 310 

44          Conditions  of 312 

44          Chemic'l  Physiology  of.818 

44         Phenomena  of. 311 

44          Temperature  of. .  :>v . . .  312 

Girdling 342,  34'3.  :;il 

Glass 121 

Glauber's  Salt 132 

Gliadin 101 

Globulin 97 

Glucose 74 

Glucosides 77,  110 

Gluten 99 

Gluten-Casein 100 

Glycerin 93 

Gourd  fruits 301 

Grains 301 

44    Ash  of. 150,373 

Grain 58 

Grape  Sugar 74 

Grasses,  ash-analyses ....157,  37ti 

prox.     4t        385 

Gravitation,  influence  on  growth.... 371 

Growth 231 

44      of  roots •!'•»"> 

44      Downward  and  upward.    ...372 

Gum,  Amount  of,  in  plants 72 

Gum  Arabic 70 

Qum  Tragacanth 71,79 

Gun  Cotton 58 

Gypsum 133 

Gyde,  Kxp.  on  root-excretion 239 

Oaberlandt,  on  vitality  of  seeds.... 306 

Haemoglobin  97 

Hallett «  pedigraa  wheat 144 


INDEX. 


XID 


H&llier,  Exp's  on  absorption  of  pig 
ments  by  plant 360 

Hazel  leaves,  lose  by  solution 190 

Heart-wood 282 

Heavy  metals 127 

Henrici's  Exp.  with  raspberry  roots.254 

Herbaceous  stems . .  282 

Honey-dew 7(5 

Hooibrenk.  artificial  fecundation.  ..295 
Horse-chestnut,  Ash-analyses  of. . .  .159 

Hybrid,  Hybridizini: 295 

Hjdrated  phosphoric  acid 117 

silica 121 

"         sulphuric  acid 116 

Hydrate  of  lime 126 

"       "  magnesia 127 

"       "  potash 12 -t 

11  soda 125 

Hydration  of  membranes 357 

Hydrochloric  acid 118 

Hydrogen 39,  112 

in  Germination 323 

Imbibition 346 

Imbibing  power 347,  348 

Imbricated 262 

Introduction , 17 

Inorganic  matter 29 

Intercellular  spaces 22(5 

Internodes 262 

Inulin 68 

Iodine  in  plants 119,  196 

"      Solution  of 59 

Iron 197 

>-  Function  of. 19;) 

Isomerism 81 

Jerusalem  Artichoke,  Cell  of 224 

Juices  of  the  Plant 330 

Kernel 302 

L:i:-p>--e 78 

Latent  buds 263 

Laiirus  C'anariensis,  Air-roots  of 257 

Laurin 90 

Layers 264 

Leached  ashes 132 

Lead  in  plants 196 

Leaf-green 110 

li    pores 285 

Leaves,  Structure  of. 283 

"      office  in  nutrition 328 

"      of  trees,  Ash  of 379 

"      under  artificial  pressure 369 

Legume 301 

Legumiu 101 

Lt-gcminous  plants 302,  304 

Legumes,  ash-analyses...  152,157,379 

4i        pro.-£.      "      387 

Leucophyll..   110 

Levulose 73 

Liebig  on  small  seeds 308 

"      "  relations  between  N  and 

P2  O5 202 

Light,  eflect  on  direction  of  growth.375 

"        "      u  germination 314 

Light  seeds,  Plants  from 307 

Lignin 57 

Lime . .  126 

"    essential  to  vegetation  172 

Lime-water 36,  126 


Linolein 00 

L'.quid  Diffusion S51 

Lithia,  Lithium 125 

"      in  plants 195 

Litter,  Ash  of 37t< 

Londet,  on  vitality  of  seeds 306 

Madder  crop 195 

Magazine,  Root  as 25 

Magnetic  oxide  of  iron 128 

Magnesia 127 

Movements  of,  in  oat 219 

Magnesium 12(5 

Maize,  ash-analyses 151,  153,  379 

"      prox.     "        387 

"      paper 57 

"      seed,  Section  of 303 

"      stalk,        "      "  268 

Maizena 63 

Malates 136 

Malate  of  lime 88 

Malic  acid 88,  89 

Malt,  Chemistry  of 319 

Maltose 75 

Manganese 128 

"         cannot  replace  iron 201 

Manna 77 

Mannite 78 

Maple,  Flow  of  sap  from 332 

sugar 7:5 

Maraarin...  99 


Matter 25 

Meadow  hay,  Ash  of. 376 

Medullary  rays 276 

Membrane-diffusion 354 

Membranes,  Influence    on    motion 

of  juices 365 

Metals 112 

Metallic  elements 12-'} 

Metapectic  acid 83 

Metarabic  acid  71 

Milk  ducts 28J 

Milieu's  test % 

Moisture,  in  Germination 313 

Molecular  Weights 48 

Molecules 48 

Monoecious  plants 294 

Monocotyledonous  seeds  303 

Monocalcic  phosphate 134 

Motion  caused  by  adhesion 350 

Mould 223 

Mucidin 101,  321 

Multiple  Proportions 48 

Mummy  wheat 305 

Muriate  of  soda 136 

Muriatic  acid Ill) 

Mustard,  Root-hairs  of. 241 

Mycose  ...   7b 

Myristin t«0 

Nasturtium,  Cells  of. 227 

Nicotiu 110 

Niter,  nitrate  of  potash 136 

Nitrates  in  plants 108,  136 

Nitrocellulose 58 

Nitrogen.  Properties  of 37 

'in  ash 112 

"  Germination 323 

"         relation    to    phosphoric 
acid 201 


HOW   CROPS    GROW. 


Nobbe  &  Sicgert,  Exp.  on  buck 
wheat 188 

Nodes 262 

Nomenclature,  Botanical 299 

Non-Metals 112 

Norton's  analyses  of  oat-plant.. 141,  204 

Notation,  Chemical 49 

Nucleus 422,  278 

Nucleolus 224 

Nat 900 

Nutrient  matters  i  n  plant,  Motion  of.340 

Nutrition  of  seedling 318 

**  "  plant 327 

Oa!,  ash-analysis 151, 153,  157,  160 

161,  102,  378 

"    prox.      "      378 

"       "         "     detailed 3SS 

"    crop,  weight  per  acre 387 

"    plant,  Composition  and  growth 

of 204,  207,  214,  217 

Oat,  proportions  of  ash  in  its  differ 
ent  parts 141 

Oats,  weight  per  bushel 102 

Offices  of  organs  of  plant 220 

Oil  in  seeds,  etc 89,  90,  394 

ik  of  mustard 114 

"  "    vitriol 42,116 

Oils,  Properties  of. 89 

Old  seeds,  Plants  from 307 

Oleic  acid 93 

Olein 90,  92 

Orders 298 

Organic  matter 29 

Organism 221 

Organs 221 

Osmose 354 

"      mechanical  effects  on  plant.. 367 

Osmometer 355 

Ovaries 293 

Ovules 293 

Oxai.at.es    136 

Oxalate  of  ammonia 86 

"      "  lime ...85,  86 

"      "     "    in  walnut 191 

Oxalic  acid 85 

Oxide  of  iron 000 

•'        "    'k  essential  to  plants 178 

**        "    "  State  of,  in  plant 193 

•'        "  manganese  in  ash 179 

Oxides  37 

of  iron,  described 127 

"      "  manganese,  described...  128 

Oxygen,  Properties  of 33 

•'       occurrence  in  ash 113 

"        in  Assimilation 326 

'*       '*  Germination 314 

Palmitic  acid 93 

Palinitin 9ii.  92 

Parenchyma 232 

Papilionaceous  plants 299 

Pappus :501 

Pea,  ash-analysis .  .152,  ir>:],  :!71» 

"    prox.    " 387 

"    ultimate  analysis 45 

P'-ariash 130 

Pecticacid 82,84 

Pectin M 

Pectoaic  aekl 82 


Pectose 81 

Pedigree  wheat 144 

Permeability  of  cells 232 

Peroxide  of  iron 128 

Petals 294 

Phaenogams 29'.  • 

Phantom  bouquets 57 

Phloridzin 77 

Phosphate  of  lime 134 

"  soda 134 

"  potash i:i4 

Phosphates .43,  44, 117,  133 

"          function  in  plants 197 

"         relation  to  albuminoids. 202 

Phosphoric  acid 38,44,  117 

"  in  oat-crop 218 

Phosphorite 135 

Phosphorized  oils 45,  92 

Phosphorus 43,117 

in  albuminoids 102 

"  fats  of  various  plants.  92 

Physics »J 

Physiology 27 

Finite. -!8 

Pistils .    .2:13 

Pith 2C.9 

"  rays 276 

Plastic  Elements  of  Nutrition 104 

Plaster  of  Paris 133 

Plumule 3-13 

Pod 301 

Pollarding 2fi  I 

Pollen 292 

Polygonum  convolvulus,  Fertilization 

of,  fig 295 

Pome . . .  301 

Porosity  of  vegetable  tissues 34(5 

Potato,  ash-analyses. . .  154,  162,  165,  377 

"      prox.  analyses :  >T 

'          "  "       detailed :W) 

4       ultimate  "        45 

'       leaf,  Pores  of,  fig -2->> 

Btem,  Section  of',  fig 2^1 

sugar 74 

'       tuber,  Structure  and  Section 

of,  fig 274,277 

Potato  tuber,  why  mealy 221; 

Potash 124,  130 

"      lye 124 

"      in  strand  and  marine  plants. .17fc 

Potassium 124 

Chloride  of. 135 

Prosenchyma -j:;2 

Protagon 93 

Protoplasm . .  224 

Protein  bodies 94,  103 

Protoxide  of  iron 127 

"    manganese 128 

Proximate  Composition  of  Crops... 3s."; 

Elements 155 

Prussic  Acid 114 

Puff-balls 2.-J2 

Pulp  of  fruits 2-.J3 

aek  Lrra^s 

(^uantitaiive  relations  among  ingre 
dients  of  plant 201 

Quart/ 120 

Quercitannic  acid L1Q 


INDEX. 


Quercite 78 

Radicle 3U3 

Red  clover  hay,  Ultimate  analysis  uf .  45 

"  Ivet,  Pigment  of 367 

"  pine,  Pith  rays  of 276 

"  snow 223 

Relations  of  Cellulose  and  Pec  ,ose 

Groups 84 

Relations  of  Fats  to  Amyloids 94 

"         "  Veg.  Acids    to   Amy 
loids 89 

Reproductive  Organs 223,  291 

liice,  ash-analysis 151, 152,  379 

"    prox.      "      387 

"       "         "     detailed aS9 

"    roots  of 25-2 

Rind 275 

Ringing  of  stems 341 

Rock  Crystal 120 

Root-action,  imitated 3(51 

"         "        in  winter 333 

"         "       Osmose  in 300 

"    cap 2S5 

"    crops,  ash-analyses 155,  377 

"       prox.     "       367,389 

"    cuttings 237 

' '    distinguished  from  stem 236 

•*    excretions £38 

"    hairs 243 

"    office  in  Nutrition 327 

44    power  of  vine. 248 

•'    Seat  of  absorptive  force  in  —  249 

"    stock 265 

Rootlets 238 

Roots,  Structure  of. 234 

"     Bursting  of 369 

1     contact  with  soil 245 

"     going  down  for  water 254 

"      Search  of  food  by 241 

"     Quantity  of 242 

Rubidium 125 

41        action  on  oat 196 

Runners 264 

Rye.  ash-analysis  150,  153,  379 

"     prox.      "      387,388 

Saccharose 72 

"        Amount  of,  in  plants —  73 

Sago 64 

Salueratus 131 

Salicin 77 

Salicornia 117,  177 

Salm-Horstmar,  Exp's  in  artificial 

soils 166 

Sal-soda 131 

Salsola 177, 183 

Salts,  Definition  of 86 

"     in  ash  of  plants 129 

"     Properties  of. 87 

Saltwort 177 

Samphire 177 

Sap 330 

"  Acid  and  alkaline.. ..366 

"  ascending 310 

"descending :m 

*'  Composition  of 337 

**  of  sunflower 338 

M  Spring  flow  of     334 

**  wood....  ...282 


Saponificaiion ,W 

Saussure,  exp.  01  mint 137 

Saxifraga  crustat  j, ..192 

Scotch  fir,  Wood-cells  of,  fig 279 

Scouring  rush 184 

Screw  pine,  Root  cap  of,  fig 236 

Sea- weeds,  Potash  in 198 

Seed 80:1 

"  vessel MOO 

Seeds,  constancy  of  composition.  ..145 

Selecting  power  of  plant 32(1,  362 

Sepals 292 

Series .298 

Sesquioxidc  of  iron 128 

"  "manganese 12$ 

Sieve-cells 280 

"    in  pith 343,345 

Silex 120 

Silica 120 

"    does  not  prevent   lodging  of 

grain 198 

"    Function  of,  in  plant 197 

"    in  ash 183 

"      "oat 198 

"      "  textile  materials 185 

"    unessential  to  plants 183 

Silicates 120 

Silicate  of  potash 120 

Silicic  acid 120 

Silicon 119 

Silk  of  maize 294 

Silver  Fir.  Roots  of 245 

Silver-grain 27« 

Skeletonized  plants 57 

Soaps 93 

Soda 125 

"     can  it  replace  potash  ? 176 

"    essential  to  ag.  plants? 172 

"    in  strand  and  marine  plants.. .177 

"     Variations  of,  in  field-crops...  173 

Soda-ash...  ...131 


Sodium 124 

Chloride  of 136 

Sorghum  sugar 73 

Soil,  Ofiices  of 329 

Soil-roots 252 

Solution  of  starch  in  Germination.. 322 

'•  for  water-culture 168 

Soluble  silica 121 

"  starch 322 

Species 296 

Spirits  of  salt 119 

Spongiolea 235 


Stamens 292 

Starch,  amount  in  plants 66 

estimation , 66 

in  wood  337 

Properties  of. 63 

sugar 74 

Testfjr 64 

unorgmized 64 

Stearic  ucid 93 

Stearin 90,  92 

Stem,  Endogenous 269 

"      Exogenous 273 

"      Structure  of. 267 

Stems 261 

Stigma 296 


XVI 


HOW    CROPS    GROW. 


Stomata 285 

Stool 205 

Straw,  ash-analyses 152,  153,  157 

"  prox.  "  .386 

Structure  of  plant 220 

Suckers 20(5 

Sugar-beet,  ash-analyses....  154.  156,  158 

"  "  detailed  analyses. . .' 389 

Sugar,  esti  niation  of. 76 

in  cereals 77 


of  milk 78 

Trommer's  test  for 75 

Sulphate  of  lime 133 

'•    potash 132 

"    soda 132 

Sulphates 43,  117,  182 

Function  of. l'.»6 

in  clover 194 

reduced  by  plant 190 

Sulphides 42 

Sulphide  of  potassium 115 

S  ulphi  tes 115 

Sulphocyanide  of  allylc 114 

Sulphur 42,  114 

"      in  oats 194 

Sulphurated  hydrogen 43,  115 

Sulphurets 42 

Sulphuric  acid 42,  116 

"  in  oat 219 

Sulphurous  acid 42,  115 

Snlphydric  acid 43,  115 

Stipercarbonate  of  soda 131 

Superphosphate  of  lime 135 

Symbols,  Chemical 47 

Tabashir 183 

Tannin 77,110 

Tao-foo 101 

Tapioca 64 

Tap-roots 237 

Tartaric  acid 88,  89 

Tartrates 13(5 

-  of  maize 294 

Teak.  Phosphate  of  lime  in 191 

Tension  in  plant 372 

Tests  for  albuminoids 96 

Textile  plants,  Ash  of 378 

Theobromin Ill 

'J'lilnxiii,  var.  calaminaris 196 

Tillering 205 

Titanic  acid 123,  195 

Titanium 123 

Tobacco,  ash-analyses 378 

"        Silica  in 1>5 

Touch-paper 136 

'J'niilrxcuntia  zebrina,  Air-roots  of.. 257 
Transformations  of  cell-contents. ..889 
Translocatiou  of  substances,  in 

plant 218 

Transplanting ~~>~> 

Triculcic  phosphate 134,  135 

Tubers 266 

Turnip,  ash-analyses 155.: 

prox.      "      

Tuscan  hat- wheat lit 

Vluinaii1  Composition  of  Vegetable 
.Mailers    

Umbelliferous  plants 201 


Unripe  seed.  Plants  from 80C 

Variation  of  ash-ingrediei  ts,  limit 
ed 147,  148 

Varieties 291 

Causes  of 144 

Vascular  bundle  of  maize  stalk, 27" 

Vascular-Ti^ene x::;;-, 

Vegetable  acids  85 

albumin f'7 

"         casein ...KK! 

cell S2v 

"         fibrin 9;» 

"          ivory 226 

"         mucilage 71 

'•         parchment 5s 

"         tissue 225.  232 

Vegetative  organs 222,  234 

Veins  of  the  leaf 2»°5 

Vine,  Bleeding  of 332 

Viola  ctdaminaris 196 

Vitality  of  roots 260 

"  seeds 305 

Vital  Principle 221 

Water,Composition  of. 63  N 

"    Estimation  of 55 

"    Formation  of 41 

"    imbibed  by  roots 248 

"  seeds 360 

"    in  air-dry  plants 55 

"     "  fresh  plants 54 

"    of  plant  affected  by  soil 369 

"     "  vegetation,  Free 55 

u    "  fci  Hygroscopic..  55 

Water-bath * 54 

Water-culture 167 

Water-sjlass 120 

Water  Boots  ...   252,  253 

Wax 89,  9C 

"   in  oat-plant..   211 

Well-water,  used  in  water-culture, 

Composition  of 171 

Wheat,  ash-analyses 150,  152,  379 

*'      prox.      "       387 

"       detailed 388 

ultimate  analyses    45 

"      gum 99 

"      straw,  proximate  analysis. . .  386 
"  "     ultimate  "       ...  45 

"      roots  of. 346,  247 

White  of  egg 96 

Wiegmann  &  Polstroff,  Exp.  with 

cress 146 

Wiltiiii: 334 

\Voltr,  Kxp.  with  buckwheat 164 

Wood 57 

Amount  of  water  iu 333 

"     Ash  of 379 

"  ceiis rn 

"      "    of  conifers 279 

41    paper 57 

Woody-liber i;;i 

"      stems 2S2 

11      tissue 2:*i 

22:;.  2.-.1 

Zuinin.  wiralte,  lioot  of. 25v 

Zanthopif/1] — lie 

Zinc...  129,181 


HOW    CROPS    GROW 


INTRODUCTION. 


The  objects  of  agriculture  are  the  production  of  certain 
plants  and  certain  animals  which  are  employed  to  feed  and 
clothe  the  human  race.  The  first  aim,  in  all  cases,  is  the 
production  of  plants. 

Nature  has  made  the  most  extensive  provision  for  the 
spontaneous  growth  of  an  immense  variety  of  vegetation ; 
but  in  those  climates  where  civilization  most  certainly  at 
tains  its  fullest  development,  man  is  obliged  to  employ  art 
to  provide  himself  with  the  kinds  and  quantities  of  vege 
table  produce  which  his  necessities  or  luxuries  demand. 
In  this  defect,  or,  rather,  neglect  of  nature,  agriculture  has 
its  origin. 

The  art  of  agriculture  consists  in  certain  practices  and 
operations  which  have  gradually  grown  out  of  an  obser 
vation  and  imitation  of  the  best  efforts  of  nature,  or  have 
been  hit  upon  accidentally. 

The  science  of  agriculture  is  the  rational  theory  and  ex 
position  of  the  successful  art. 

Strictly  considered,  the  art  and  science  of  agriculture 
are  of  equal  age,  and  have  grown  together  from  the  ear 
liest  times.  Those  who  first  cultivated  the  soil  by  dig- 
17 


18  HOW   CROPS    GROW. 

ging,  planting,  manuring,  and  irrigating,  had  their  suffi 
cient  reason  for  every  step.  In  all  cases,  thought  goes 
before  work,  and  the  intelligent  workman  always  lias  a 
theory  upon  which  his  practice  is  planned.  No  farm 
was  ever  conducted  with  jut  physiology,  chemistry,  and 
physics,  any  more  than  an  aqueduct  or  a  railway  WF»S  ever 
built  without  mathematics  and  mechanics.  Every  success 
ful  fanner  is,  tc  some  extent,  a  scientific  man.  Let  him 
throw  away  the  knowledge  of  facts  and  the  knowledge  of 
principles  which  constitute  his  science,  and  he  has  lost  the 
elements  of  his  success.  The  farmer  without  his  reasons, 
his  theory,  his  science,  can  have  no  plan ;  and  these  want 
ing,  agriculture  would  be  as  complete  a  failure  with  him 
as  it  would  be  with  a  man  of  mere  science,  destitute  of 
manual,  financial,  and  executive  skill. 

Other  qualifications  being  equal,  the  more  advanced  and 
complete  the  theory  of  which  the  farmer  is  the  master,  the 
more  successful  must  be  his  farming.  The  more  he  knows, 
the  more  he  can  do.  The  more  deeply,  comprehensively, 
and  clearly  he  can  think,  the  more  economically  and  ad 
vantageously  can  he  work. 

That  there  is  any  opposition  or  conflict  between  science 
and  art,  between  theory  and  practice,  is  a  delusive  error. 
They  are,  as  they  ever  have  been  and  ever  must  be,  in  the 
fullest  harmony.  If  they  appear  to  jar  or  stand  in  con 
tradiction,  it  is  because  we  have  something  false  or  incom 
plete  in  what  we  call  our  science  or  our  art ;  or  else  we  do  not 
percoive  correctly,  but  are  misled  by  the  narrowness  and 
aberrations  of  our  vision.  It  is  often  said  of  a  machine, 
that  it  was  good  in  theory,  but  failed  in  practice.  This  is 
as  untrue  as  untrue  can  be.  If  a  machine  has  failed  in 
practice,  it  is  because  it  was  imperfect  in  theory.  It  should 
be  said  of  such  n  failure — the  machine  was  good,  judged 
by  the  best  theory  known  to  its  inventor,  but  its  incapacity 
tc  work  demonstrates  that  the  theory  had  a  flaw. 

But,  although  art  and  science  aro    hus  inseparable,  it 


1 9 

must  not  be  forgotten  that  their  growth  is  net  altogether 
parallel.  There  are  facts  in  art  for  which  science  can,  as 
yet,  furnish  no  adequate  explanation.  Art,  though  no 
older  than  science,  grew  at  first  more  rapidly  in  vigor  and 
in  stature.  Agriculture  was  practised  hundreds  and 
thousands  of  years  ago,  with  a  success  that  does  not  com 
pare  unfavorably  with  ours.  Nearly  all  the  essential  points 
of  modern  cultivation  were  regarded  by  the  Romans  be 
fore  the  Christian  era.  The  annals  of  the  Chinese  show 
that  their  wonderful  skill  and  knowledge  were  in  use  at  a 
vastly  earlier  date. 

So  much  of  science  as  can  be  attained  through  man's 
unaided  senses,  reached  considerable  perfection  early  in 
the  world's  history.  But  that  part  of  science  which  re 
lates  to  things  invisible  to  the  unassisted  eye,  could  not 
be  developed  until  the  telescope  and  the  microscope  had 
been  invented,  until  the  increasing  experience  of  man  and 
his  improved  art  had  created  and  made  cheap  the  other  in 
ventions  by  whose  aid  the  mind  can  penetrate  the  veil  of 
nature.  Art,  guided  at  first  by  a  very  crude  and  imperfectly 
developed  science,  has,  within  a  comparatively  recent  pe 
riod,  multiplied  those  instruments  and  means  of  research 
whereby  science  has  expanded  to  her  present  proportions. 

The  progress  of  agriculture  is  the  joint  work  of  theory 
and  practice.  In  many  departments  great  advances  have 
been  made  during  the  last  hundred  years ;  especially  is  this 
true  in  all  that  relates  to  implements  and  machines,  and  to 
the  improvement  of  domestic  animals.  It  is,  however,  in 
just  these  departments  that  an  improved  theory  has  had 
sway.  More  recent  is  the  development  of  agriculture  in  its 
chemical  and  physiological  aspects.  In  these  directions  the 
present  century,  or  we  might  almost  say  the  last  30  years, 
has  seen  more  accomplished  than  all  previous  time. 

The  first  book  in  the  English  language  on  the  subjects 
which  occupy  a  good  part  of  the  following  pages,  was 
written  by  a  Scotch  nobleman,  the  Earl  of  Dundonald,  and 


20  HOW   CROPS   GEOW. 

was  published  at  London  in  1795.  It  was  entitled :  "  A 
Treatise  showing  the  Intimate  Connection  that  subsist? 
between  Agriculture  and  Chemistry."  The  learned  Earl 
in  his  Introduction  remarked  that  "  the  slow  progress 
which  agriculture  has  hitherto  made  as  a  science  is  to  bo 
ascribed  to  a  want  of  education  on  the  part  of  the  culti 
vators  of  the  soil,  and  the  want  of  knowledge  in  such  au 
thors  as  have  written  on  agriculture,  of  the  intimate  con 
nection  that  subsists  between  the  science  and  that  of 
chemistry.  Indeed,  there  is  no  operation  or  process,  not 
merely  mechanical,  that  does  not  depend  on  chemistry, 
which  is  defined  to  be  a  knowledge  of  the  properties  of 
bodies,  and  of  the  effects  resulting  from  their  different 
combinations."  Earl  Dundonald  could  not  fail  to  see  that 
chemistry  was  ere  long  to  open  a  splendid  future  for  the 
ancient  art  that  always  had  been  and  always  is  to  be  the 
prime  support  of  the  nations.  But  when  he  wrote,  no 
longer  than  seventy-two  years  ago,  how  feeble  was  the 
light  that  chemistry  could  throw  upon  the  fundamental 
questions  of  agricultural  science  !  The  chemical  nature  of 
atmospheric  air  was  then  a  discovery  of  barely  20  years' 
standing.  The  composition  of  water  had  been  known  but 
12  years.  The  only  account  of  the  composition  of  plants 
that  Earl  Dundonald  could  give,  was  the  following: 
"Vegetables  consist  of  mucilaginous  matter,  resinous 
matter,  matter  analogous  to  that  of  animals,  and  some  pro 
portion  of  oil.  *  *  Besides  these,  vegetables  contain 
earthy  matters,  formerly  held  in  solution  in  the  newly 
taken-in  juices  of  the  growing  vegetable."  To  be  sure  he 
explains  by  mentioning  on  subsequent  pages  that  starcli 
belongs  to  the  mucilaginous  matters,  and  that,  on  analysis 
by  fire,  vegetables  yield  soluble  alkaline  salts  and  insolu 
ble  phosphate  of  lime.  But  these  salts,  he  held,  were 
formed  in  the  process  of  burning,  their  lime  exceptcd,  and 
the  fact  of  their  Veing  taken  from  the  soil  and  constituting 
tl»e  indispensable  food  of  plants,  his  Lordship  was  uuao- 


INTRODUCTION  21 

quainted  with.  The  gist  of  agricultural  chemistry  with 
him  was,  that  plants  are  "composed  of  gases  with  a  small 
proportion  of  calcareous  matter ;  "  for  "  although  this 
discovery  may  appear  to  be  of  small  moment  to  the  prac 
tical  farmer,  yet  it  is  well  deserving  of  his  attention  and 
notice,  as  it  throws  great  light  on  the  nature  and  food  of 
vegetables."  The  fact  being  then  known  that  plants  ab 
sorb  carbonic  acid  from  the  air,  and  employ  its  carbon  in 
their  growth,  the  theory  was  held  that  fertilizers  operate 
by  promoting  the  conversion  of  the  organic  matter  of  the 
soil  or  of  composts  into  gases,  or  into  soluble  humus, 
which  were  considered  to  be  the  food  of  plants. 

The  first  accurate  analysis  of  a  vegetable  substance  was 
not  accomplished  until  15  years  after  the  publication  of 
Dundonald's  Treatise,  and  another  like  period  passed  be 
fore  the  means  of  rapidly  multiplying  good  analyses  had 
been  worked  out  by  Liebig.  So  late  as  1838,  the  Gottingen 
Academy  offered  a  prize  for  a  satisfactory  solution  of  the 
then  vexed  question  whether  the  ingredients  of  ashes  are 
essential  to  vegetable  growth.  It  is,  in  fact,  during  the  last 
30  years  that  agricultural  chemistry  has  come  to  rest  on 
sure  foundations.  Our  knowledge  of  the  structure  and 
physiology  of  plants  is  of  like  recent  development. 
What  immense  practical  benefit  the  farmer  has  gathered 
from  this  advance  of  science  !  The  dense  populations  of 
Great  Britain,  Belgium,  Holland,  and  Saxony,  can  attest 
the  fact.  Chemistry  has  ascertained  what  vegetation  ab 
solutely  demands  for  its  growth,  and  points  out  a  multitude 
of  sources  whence  the  requisite  materials  for  crops  can  be 
derived.  To  be  sure,  Cato  and  Columella  knew  that  ashes,, 
bones,  bird-dung  and  green  manuring,  as  well  as  drain 
age  and  aeration  of  the  soil,  were  good  for  crops ;  but 
that  carbonic  acid,  potash,  phosphate  of  lime,  and  com 
pounds  of  nitrogen,  are  the  chief  pabulum  of  vegetation, 
they  did  not  know.  They  did  not  know  that  the  atmos 
phere  dissolves  the  rocks,  and  converts  inert  stone  into 


22  HOW   CROPS   GROW. 

nutritive  soil.  These  grand  principles,  understood  in  many 
of  their  details,  are  an  inestimable  boon  to  agriculture, 
and  intelligent  farmers  have  not  been  slow  to  apply  them 
in  practice.  The  vast  trade  in  phosphatic  and  Peruvian 
guano,  and  in  nitrate  of  soda;  the  great  manufactures  of 
oil  of  vitriol,  of  superphosphate  of  lime,  of  fish  fertilizers ; 
and  the  mining  of  fossil  bones  and  of  potash  salts,  are 
largely  or  entirely  industries  based  upon  and  controlled 
by  chemistry  in  the  service  of  agriculture. 

Every  day  is  now  the  witness  of  new  advances.  The 
means  of  investigation,  which,  in  the  hands  of  the  scien 
tific  experimenter,  have  created  within  the  writer's  mem 
ory  such  arts  as  photography  and  electro-metallurgy,  and 
have  produced  the  steam  engine  and  magnetic  telegraph, 
are  working  and  shall  continue  to  work  progress  in  agri 
culture.  This  improvement  will  not  consist  so  much  in 
any  remarkable  discoveries  that  shall  enable  us  "to  grow 
two  blades  of  grass  where  but  one  grew  before,"  but  in 
the  gradual  disclosure  of  the  reasons  of  that  which  we 
have  long  known,  or  believed  we  knew,  in  the  clear  sepa 
ration  of  the  true  from  the  seemingly  true,  and  in  the  ex 
change  of  a  wearying  uncertainty  for  settled  and  positive 
knowledge. 

It  is  the  boast  of  some  who  affect  to  glory  in  the  suf 
ficiency  of  practice  and  decry  theory,  that  the  former  is 
based  upon  experience,  which  is  the  only  safe  guide.  But 
this  is  a  one-sided  view  of  the  matter.  Theory  is  also 
based  upon  experience,  if  it  be  truly  scientific.  The  vaga- 
rizing  of  an  ignorant  and  undisciplined  mind  is  not  theory. 
Theory,  in  the  good  and  proper  sense,  is  always  a  deduc 
tion  from  facts,  the  best  deduction  of  which  the  stock  of 
facts  in  onr  possession  admits.  It  is  the  interpretation  of 
facts.  It  is  the  expression  of  the  ideas  which  facts  awaken 
when  submitted  to  a  fertile  imagination  and  well-balanced 
judgment.  A  scientific  theory  is  intended  for  the  nearest 
poss'ble  approach  to  the  truth.  Theory  is  confessedly  im- 


INTRODUCTION.  28 

perfect,  because  our  knowledge  of  facts  is  incomplete,  our 
mentril  insight  weak,  and  our  judgment  fallible.  But  the 
scientific  theory  which  is  framed  by  the  contributions  of  a 
multitude  of  earnest  thinkers  and  workers,  among  whom 
are  likely  to  be  the  most  gifted  intellects  and  most  skillful 
hands,  is,  in  these  days,  to  a  great  extent  worthy  of  the 
Divine  truth  in  nature,  of  which  it  is  the  completest  hu 
man  conception  and  expression. 

Science  employs,  in  effecting  its  progress,  essentially  the 
same  methods  that  are  used  by  merely  practical  men. 
Its  success  is  commonly  more  rapid  and  brilliant,  because 
its  instruments  of  observation  are  finer  and  more  skillfully 
handled;  because  it  experiments  more  industriously  and 
variedly,  thus  commanding  a  wider  and  more  fruitful  ex 
perience  ;  because  it  usually  brings  a  more  cultivated  im 
agination  and  a  more  disciplined  judgment  to  bear  upon 
its  work.  The  devotion  of  a  life  to  discovery  or  invention 
is  sure  to  yield  greater  results  than  a  desultory  applica 
tion  made  in  the  intervals  of  other  absorbing  pursuits.  It 
is  then  for  the  interest  of  the  farmer  to  avail  himself  of 
the  labors  of  the  man  of  science,  when  the  latter  is  willing 
to  inform  himself  in  the  details  of  practice,  so  as  rightly 
to  comprehend  the  questions  which  press  for  a  solution. 

It  is  characteristic  of  our  time  that  large  associations  of  practical 
agriculturists  have  recognized  the  immediate  pecuniary  advantage  to  be 
derived  from  the  application  of  science  to  their  art.  This  was  first  done 
at  Edinburgh,  in  1843,  by  the  establishment  of  the  "Agricultural  Chem 
istry  Association  of  Scotland." 

This  organization  limited  itself  to  a  duration  of  five  years.  At  the 
expiration  of  that  time,  its  labors,  which  had  been  ably  conducted  by 
Prof.  James  F.  W.  Johnston,  were  assumed  by  the  Highland  aud  Agri 
cultural  Society  of  Scotland,  and  have  been  prosecuted  up  to  the  present 
day  by  Dr.  Anderson.  The  Royal  Ag'l  Soc.  of  England  began  to  employ  a 
consulting  chemist,  Dr.  Lyou  Play  fair,  in  1843;  and  since  1848  mo.-t 
valuable  investigations,  by  Prof.  Way  and  Dr.  Vcelcker,  have  regularly 
appeared  in  its  journal.  Other  British  Ag'l  Societies  have  followed  these 
examples  with  more  or  less  effect. 

It  is,  however,  in  Germany  that  the  most  extensive  and  well-organized 
efforts  have  been  made  by  associations  of  agriculturists  to  help  theii 


24  HOW    CROPS    GROW. 

practice  by  developing  theory.  In  1851  the  Agricultural  Society  of  Leip 
zig,  (Leipziger  Oeconomische  Societcet),  established  au  Ag'l  Experiment 
Stctitm  on  its  farm  at  Moeckeru,  near  that  city.  This  example  was  soon 
imitated  in  ether  parts  of  Germany  and  the  neighboring  countries;  and 
at  the  present,  writ. ing,  1867,  there  are  of  similar  Experiment  Stations  in 
operation — in  Prussia  10,  in  Saxony  4,  in  Bavaria  3,  in  Austria  3,  in 
Brunswick,  Hesse,  Thuringia,  An  halt,  Wirtemberg,  Baden,  and  Sweden,  1 
each,  making  a  total  of  36,  chiefly  sustained  by,  and  operating  in,  the  in- 
to  rest  of  the  agriculturists  of  those  countries.  These  stations  give  con 
stant  employment  to  60  chemists  and  vegetable  physiologi-ts,  of  whom 
a  large  number  are  occupied  largely  or  exclusively  with  theoretical  in 
vestigations,  while  the  work  of  others  is  devoted  to  more  practical  mat 
ters,  as  testing  the  value  of  commercial  fertilizers.  Since  1859  a  journal, 
Die  LatidwirthschaftUclien  Verwctu-Stationat,  (Ag'l  Exp.  Stations),  has 
been  published  as  the  organ  of  these  establishments,  and  the  9  volumes 
now  completed,  together  with  the  numerous  Reports  of  the  Stations 
themselves,  have  largely  contributed  the  facts  that  are  made  use  of  in 
the  following  pages. 

In  this  country  some  similar  enterprises  have  been  attempted,  but 
have  not  been  supported  with  a  sufficient  combination  of  talent  and  pe 
cuniary  outlay  to  ensure  any  striking  success  in  the  direction  of  agri 
cultural  chemistry.  An  imitation  of  the  example  set  by  European  as 
sociations  is  well  worthy  the  consideration  of  our  State  Ag'l  Societies, 
many  of  which  could  easily  command  the  funds  for  such  an  enterprise. 
It  would  be  found  that  such  a  use  of  their  resources  would  speedily 
strengthen  their  hold  on  the  interest  and  regard  of  the  communities 
they  represent. 

Agricultural  science,  in  its  widest  scope,  comprehends  a 
vast  range  of  subjects.  It  includes  something  from  nearly 
every  department  of  human  learning. 

The  natural  sciences  of  geology,  meteorology,  mechan 
ics,  physics,  chemistry,  botany,  zoology  and  physiology, 
are  most  intimately  related  to  it.  It  is  not  less  concerned 
with  social  and  political  economy,  with  commerce  and 
law.  In  the  treatises  of  which  this  is  the  first,  it  will  not 
be  attempted  to  cover  nearly  all  this  ground,  but  seme 
account  will  be  given  of  certain  subjects  whose  under 
standing  promises  to  be  of  the  nio-t  direct  service  to  the 
agriculturist.  The  theory  of  agriculture,  as  founded  on 
chemical,  physical,  and  physiological  science,  is  the  topic 
of  this  and  the  succeeding  volume. 


INTKODTjriTION.  25 

Some  preliminary  propositions  and  definitions  may  be 
(serviceable  to  the  reader. 

Science  deals  with  matter  and  force. 

Matter  is  that  which  has  weight  and  bulk. 

Force  is  the  cause  of  changes  in  matter — it  is  appre 
ciable  only  by  its  effects  upon  matter. 

Force  resides  in  and  is  inseparable  from  matter. 

Force  manifests  itself  in  motion. 

All  matter  is  perpetually  animated  by  force — is  there 
fore  never  at  rest.  What  we  call  rest  in  matter  is  simply 
motion  too  fine  for  our  perceptions. 

The  different  kinds  of  matter  known  to  science  have 
been  resolved  into  not  more  than  62  elements  or  simple 
substances. 

Elements,  or  ultimate  elements,  are  forms  of  matter 
which  have  thus  far  resisted  all  attempts  at  their  simplifi 
cation. 

In  ordinary  life  we  commonly  encounter  but  12  elements 
in  their  elementary  state,  viz. : 

Oxygen,  Mercury, 

Nitrogen,  .  Copper, 

Sulphur,  Lead, 

Carbon,  Tin, 

Iron,  Silver, 

Zinc,  Gold. 

The  numberless  other  substances  with  which  we  are 
familiar,  are  mostly  compounds  of  the  above,  or  of  12 
other  elements,  viz. : 

Hydrogen,  Calcium, 

Phosphorus,  Magnesium, 

Chlorine,  Aluminum, 

Silicon,  Manganese, 

Potassium,  Chromium, 

Sodium,  Nickel 


26 


HOW   CROPS    GROW. 


We  distinguish  a  number  of  forces,  which,  acting  on  or 
through  matter,  produce  all  material  phenomena.  In  the 
subjoined  scheme  the  recognized  forces  are  to  some  ex 
tent  classified  and  defined,  in  a  manner  that  may  prove 
useful  to  the  reader. 


Act  at  sensi- 
!)U;  and  in 

Repulsive     HEAT                     }  Radiant 

sensible 
distances 

UtracUve|                                                ^ 
Repulsive  (  M 

GRAVITATION       Cosmical 

Physical 

COHESION            1 

Act   only  at 

CRYSTALLIZATION 

insensible    • 
distances 

Attractive  -i 

ADHESION 

SOLUTION 

^Molecular 

OSMOSE 

AFFINITY 

Atomic         Chemical 

"  VITALITY            "  Organic        Physiological 

The  sciences  that  more  immediately  relate  to  agricul 
ture  are: 

I. — Physics  or  natural  philosophy, — the  science  which 
considers  the  general  properties  of  matter  and  such  of  its 
phenomena  as  are  not  accompanied  by  essential  change 
in  its  obvious  qualities.  All  the  forces  in  the  preceding 
scheme,  save  the  last  two,  manifest  themselves  through 
matter  without  destroying  or  masking  the  matter  itself. 
Iron  may  be  hot,  luminous,  or  magnetic,  may  fall  to  the 
ground,  be  melted,  welded,  and  crystallized ;  but  it  remains 
iron,  and  is  at  once  recognized  as  such.  The  forces  whose 
play  does  not  disturb  the  evident  characters  of  substances 
are  physical. 

II. — Chemistry, — the  science  which  studies  the  proper 
ties  peculiar  to  the  various  kinds  of  matter,  and  those 
phenomena  which  are  accompanied  by  a  fundamental 
change  in  the  matter  acted  on.  Iron  rusts,  wood  burns, 
and  both  lose  all  the  external  characters  that  serve  for 
their  identification.  They  are,  in  fact,  converted  into  other 
substances.  Affinity,  or  chemical  affinity,  unites  two  or 
more  elements  into  compounds,  unites  compounds  together 
into  more  complex  compounds  j  and,  under  the  influence  of 


INTRODUCTION.  27    , 

heat,  light,  and  other  agencies,  is  annulled  or  overcome,  so 
that  compounds  resolve  themselves  into  simpler  combina 
tions  or  into  their  elements.  Chemistry  is  the  science  of 
composition  and  decomposition ;  it  considers  the  laws  and 
results  of  affinity. 

III. — Physiology,  which  unfolds  the  laws  of  the  devel 
opment,  sustenance,  and  death,  of  living  organisms. 

When  we  assert  that  the  object  of  agriculture  is  to  de 
velop  from  the  soil  the  greatest  possible  amount  of  cer 
tain  kinds  of  vegetable  and  animal  produce  at  the  least 
cost,  we  suggest  the  topics  which  are  most  important  for 
the  agriculturist  to  understand. 

The  farmer  deals  with  the  plant,  with  the  soil,  with  ma 
nures.  These  stand  in  close  relations  to  each  other,  and 
to  the  atmosphere  which  constantly  surrounds  and  acts 
upon  them.  How  the  plant  grows, — the  conditions  under 
which  it  flourishes  or  suffers  detriment, — the  materials 
of  which  it  is  made, — the  mode  of  its  construction  and 
organization, — how  it  feeds  upon  the  soil  and  air, — how  it 
serves  as  food  to  animals, — how  the  air,  soil,  plant,  and 
animal,  stand  related  to  each  other  in  a  perpetual  round 
of  the  most  beautiful  and  wonderful  transformations, — 
these  are  some  of  the  grand  questions  that  come  before 
us ;  and  they  are  not  less  interesting  to  the  philosopher 
or  man  of  culture,  than  important  to  the  farmer  who 
depends  upon  their  practical  solution  for  his  comfort ;  or 
to  the  statesman,  who  regards  them  in  their  bearings 
upon  the  weightiest  of  political  considerations. 


DIVISION    I. 

CHEMICAL  COMPOSITION  OF  THE  PLAINT, 

CHAPTER    I. 
THE    VOLATILE    PART    OF    PLANTS. 

§1- 

DISTINCTIONS    AND    DEFINITIONS. 

ORGANIC  AND  INORGANIC  MATTER. — All  matter  may  be 
divided  into  two  great  classes — Organic  and  Inorganic. 

Organic  matter  is  the  product  of  growth,  or  of  vital 
organization,  whether  vegetable  or  animal.  It  is  mostly 
combustible,  i.  e.,  it  may  be  easily  set  on  fire,  and  burns 
away  into  invisible  gases.  Organic  matter  either  itself 
constitutes  the  organs  of  life  and  growth,  and  has  a  pecu 
liar  organized  structure,  inimitable  by  art, — is  made  up  of 
cells,  tubes  or  fibres,  (wood  and  flesh) ;  or  else  is  a  mere 
result  or  product  of  the  vital  processes,  and  destitute  of 
this  structure  (sugar  and  fat). 

All  matter  which  is  not  a  part  or  product  of  a  living 
organism  is  inorganic  or  mineral  matter  (rocks,  soils,  wa 
ter,  and  air).  Most  of  the  naturally  occurring  forms  of 
inorganic  matter  which  directly  concern  agricultural  chem 
istry  are  incombustible,  and  destitute  of  anything  like  or- 
ganic  structure. 

By  the  processes  of  combustion  and  decay,  organic  mat 
ter  is  disorganized  or  converted  into  inorganic  matter,, 
while,  on  the  contrary,  by  vegetable  growth  inorganic 
matter  is  organized,  and  becomes  organic. 
29 


30  HOW   CROPS   GROW. 

Organic  matters  are  in  general  characterized  by  com 
plexity  of  constitution,  and  are  exceedingly  numerous  and 
various;  while  inorganic  bodies  are  of  simpler  composi 
tion,  and  comparatively  few  in  number. 

VOLATILE  AND  FIXED  MATTER. — All  plants  and  animals, 
taken  as  a  whole,  and  all  of  their  organs,  consist  of  a  vola- 
ti.e  and  a  fixed  part,  which  may  be  separated  by  burning ; 
the  former — usually  by  far  the  larger  share — passing  into, 
and  mingling  with  the  air  as  invisible  gases ;  the  latter — 
forming,  in  general,  but  from  one  to  five  per  cent  of  the 
whole — remaining  as  ashes. 

EXPERIMENT  1.— A  splinter  of  wood  heated  in  the  flame  of  a  lamp 
takes  fire,  burns,  and  yields  volatile  matter,  which  consumes  with  flame, 
and  ashes,  which  are  the  only  visible  residue  of  the  combustion. 

Many  organic  bodies,  products  of  life,  but  not  essential 
vital  organs,  as  sugar,  citric  acid,  etc.,  are  completely 
volatile  when  in  a  state  of  purity,  and  leave  no  ash. 

CURRENT  USE  OF  THE  TERMS  ORGANIC  AND  INORGAN 
IC. — It  is  usual  among  agricultural  writers  to  confine  the 
term  organic  to  the  volatile  or  destructible  portion  of  vege 
table  and  animal  bodies,  and  to  designate  their  ash-ingre 
dients  as  inorganic  matter.  This  use  of  the  words  is  ex 
tremely  inaccurate.  What  is  found  in  the  ashes  of  a  tree 
or  of  a  seed,  in  so  far  as  it  was  an  essential  part  of  the  or 
ganism,  was  as  truly  organic  as  the  volatile  portion,  and  by 
submitting  organic  bodies  to  fire,  they  may  be  entirely 
converted  into  inorganic  matter,  the  volatile  as  well  as  the 
fixed  parts. 

ULTIMATE  ELEMENTS  THAT  CONSTITUTE  THE  PLANT. — 
Chemistry  has  demonstated  th:it  the  volatile  and  destruct 
ible  part  of  organic  bodies  is  made  up  chiefly  of  four  sub 
stances,  viz. :  carbon,  oxygen,  hydrogen,  and  nitrogen, 
and  contains  two  other  elements  in  lesser  quantity,  viz. : 
sulphur  and  phosphorus.  In  the  ash  we  may  find  phos 
phorus,  sulphur,  silicon,  chlorine,  potassium,  sodium,  cal« 


THE  VOLATILE  PART  OF  PLANTS.  31 

ciuni,  magnesium,  iron,  and  manganese,  as  well  as  oxygen, 
carbon,  and  nitrogen.* 

These  fourteen  bodies  are  elements,  which  means  in 
chemical  language,  that  they  cannot  be  resolved  into  other 
substances.  All  the  varieties  of  vegetable  and  animal 
matter  are  compounds, — are  composed  of  and  may  be  re 
solved  into  these  elements. 

The  above  fourteen  .elements  being  essential  to  the  or 
ganism  of  every  plant  and  animal,  it  is  of  the  highest  im 
portance  to  make  a  minute  study  of  their  properties. 

§2. 
ELEMENTS    OF    THE    VOLATILE    PART    OF    PLANTS. 

For  the  sake  of  convenience  we  shall  first  consider  the 
elements  which  constitute  the  destructible  part  of  plants, 
viz. : 

Carbon,  Hydrogen, 

Oxygen,  Sulphur, 

Nitrogen,  Phosphorus. 

The  elements  which  belong  exclusively  to  the  ash  will 
be  noticed  in  a  subsequent  chapter. 

Carbon,  in  the  free  state,  is  a  solid.  We  are  familiar 
with  it  in  several  forms,  as  lamp-black,  charcoal,  anthracite 
coal,  black-lead,  and  diamond.  Notwithstanding  the 
substances  just  nanied  present  great  diversities  of  appear 
ance  and  physical  characters,  they  are  identical  in  a  cer 
tain  chemical  sense,  as  by  burning  they  all  yield  the  same 
product^  viz. :  carbonic  acid  gas. 

That  carbon  constitutes  a  large  part  of  plants  is  evident 
from  the  fact  that  it  remains  in  a  tolerably  pure  state  after 
the  incomplete  burning  of  wood,  as  is  illustrated  in  the 
preparation  of  charcoal. 

*  Rarely,  or  to  a  slight  extent,  lithium,  rubidium,  iodine,  bromine,  fluorine^ 
Kannm,  copper,  zinc,  and  titanium. 


32  HOW  CROPS   GROW. 

EXP.  2.— If  a  splinter  of  dry  pir,e  wood  be  set  on  fire  and  toe 
burning  end  be  gradually  passed  into  the  mouth  of  a  narrow  tube,  (see 
figure  1,)  whereby  the  supply  of  air  is  cut  off,  or  if  it  be 
thrust  into  sand,  the  burning  is  incomplete,  and  a  stick  of 
charcoal  remains. 

Carbonization  and  charring  are  terms  used  to 
express  the  blackening  of  organic  bodies  by  heat, 
and  are  due  to  the  separation  of  carbon  in  the 
free  or  uncombined  state. 

The  presence  of  carbon  in  animal  matters  also  is 
shown  by  subjecting  them  to  incomplete  com 
bustion. 

EXP.  3.— Hold  a  knife-blade  in  the  flame  of  a  tallow  candle ; 
the  full  access  of  air  is  thus  prevented,— a  portion  of  carbon 
escapes  combustion,  and  is  deposited  on  the  blade  in  the  form    Flg>    ' 
of  lamp-black. 

Oil  of  turpentine  and  petroleum  (kerosene,)  contain  so 
much  carbon  that  a  portion  escapes  in  the  free  state  as 
smoke,  when  they  are  set  on  fire. 

When  bones  are  strongly  heated  in  closely  covered  iron 
pots,  until  they  cease  yielding  any  vapors,  there  remains 
in  the  vessels  a  mixture  of  impure  carbon  with  the  earthy 
matter  (phosphate  of  lime)  of  the  bones,  which  is  largely 
used  in  the  arts,  chiefly  for  refining  sugar,  but  also  in  the 
manufacture  of  fertilizers  under  the  name  of  animal  char 
coal,  or  bone-black. 

Lignite,  bituminous  coal,  coke — the  porous,  hard,  and 
lustrous  mass  left  when  bituminous  coal  is  headed  with  a 
limited  access  of  air,  and  the  metallic  appearing  gas-carbon 
that  is  found  lining  the  iron  cylinders  in  which  illuminat 
ing  coal-gas  is  prepared,  consist  chiefly  of  carbon.  They 
usually  contain  more  or  less  incombustible  matters,  as  well 
as  oxygen,  hydrogen,  and  nitrogen. 

The  different  forms  of  carbon  possess  a  greater  or  less  de 
gree  of  porosity  and  hardness,  according  to  their  origin 
and  the  temperature  at  which  they  are  prepared. 

Carbon,  in  most  of  its  forms,  is  extremely  indestructible 


THE  VOLATILE  PART  OF  PLANTS.  33 

unless  exposed  to  an  elevated  temperature.  Hence  stakes 
and  fence  posts,  if  charred  before  setting  in  the  ground, 
last  longer  than  when  this  treatment  is  neglected. 

The  porous  varieties  of  carbon,  especially  wood  charcoal 
and  bone-black,  have  a  remarkable  power  of  absorbing 
gases  and  coloring  matters,  which  is  taken  advantage  of 
in  the  refining  of  sugar.  They  also  destroy  noisome 
odors,  and  are  therefore  used  for  purposes  of  disinfection. 

Carbon  is  the  characteristic  ingredient  of  all  organic 
compounds.  There  is  no  single  substance  that  is  the  ex 
clusive  result  of  vital  organization,  no  ingredient  of  the 
animal  or  vegetable  produced  by  their  growth,  that  does 
not  contain  this  element. 

Oxygen. — Carbon  is  a  solid,  and  is  recognized  by  our 
senses  of  sight  and  feeling.  Oxygen,  on  the  other  hand, 
is  invisible,  odorless,  tasteless,  and  not  distinguishable 
in  any  way  from  ordinary  air  by  the  unassisted  senses.  It 
is  an  air  or  gas. 

It  exists  in  the  free  (uncombined)  state  in  the  atmos 
phere  we  breathe,  but  there  is  no  means  of  obtaining  it 
pure  except  from  some  of  its  compounds.  Many  metals 
unite  readily  with  oxygen,  forming  compounds  (oxides) 
which  by  heat  separate  again  into  their  ingredients,  and 
thus  furnish  the  means  of  procuring  pure  oxygen.  Iron 
and  copper  when  strongly  heated  and  exposed  to  the  air 
acquire  'oxygen,  but  from  the  oxides  of  these  metals 
(forge  cinder,  copper  scale,)  it  is  not  possible  to  separate 
pure -oxygen.  If,  however,  the  metal  mercury  (quicksil 
ver)  be  kept  for  a  long  time  at  a  boiling  heat,  it  is  slowly 
converted  into  a  red  powder  (red  precipitate  or  oxide  of 
mercury),  which  on  being  more  strongly  heated  is  decom 
posed,  yielding  metallic  mercury  and  gaseous  oxygen  in 
a  pure  state. 

The  substance  usually  employed  as  the  most  convenient 
source  of  oxygen  gas  is  a  white  salt,  the  chlorate  of  pot- 
2* 


34 


HOW    CROPS    GROW. 


ash.     Exposed  to  heat,  this  body  melts,  and  presently 
evolves  oxygen  in  great  abundance. 

EXP.  4. — The  following  figure  illustrates  the  apparatus  employed  for 
preparing  and  collecting  this  gas. 

A  tube  of  difficultly  fusible  glass,  8  inches  long  and  %  inch  wide,  con 
tains  the  oxide  of  mercury  or  chlorate  of  potash.*  To  its  mouth  is  con 
nected,  air-tight,  by  a  cork,  a  narrow  tube,  the  free  extremity  of  which 
passes  under  the  shelf  of  a  tub  nearly  filled  with  water.  The  shelf  has 
beneath,  a  saucer-shaped  cavity  opening  above  by  a  narrow  orifice,  over 
which  a  bottle  filled  with  water  is  inverted.  Heat  being  applied  to  the 


Fig.  2. 

wide  tube,  the  common  air  it  contains  is  first  expelled,  and  presently, 
oxygen  bubbles  rapidly  into  the  bottle  and  displaces  the  water.  When 
the  bottle  is  full,  it  may  be  corked  and  set  aside,  and  its  place  supplied 
by  another.  Fill  four  pint  bottles  with  the  gas,  and  set  them  aside  with 
their  mouths  in  tumblers  of  water.  From  one  ounce  of  chlorate  of  pot 
ash  about  a  gallon  of  oxygen  gas  may  be  thus  obtained,  which  is  not 
quite  pure  at  first,  but  becomes  nearly  so  on  standing  over  water  for 
some  hours.  When  the  escape  of  gas  becomes  slow  and  cannot  be 
quickened  by  increased  heat,  remove  the  delivery-tube  from  the  water, 
to  prevent  the  latter  receding  and  breaking  the  apparatus. 


*  The  chlorate  of  potash  is  best  mixed  with  about  one-quarter  ita  weight  of 
powdered  black  oxide  of  manganese,  as  this»  facilitates  the  preparation,  and  ren 
ders  the  heat  of  a  common  spirit  lamp  sufficient. 


THE  VOLATILE  PART  OF  PLANTS.  35 

A&  this  gas  makes  no  peculiar  impressions  on  the  senses, 
we  employ  its  behavior  towards  other  bodies'for  its  recog 
nition. 

EXP.  5. — Place  a  burning  splinter  of  wood  in  a  vessel  of  oxygen  (lift 
ed  fcrthat  purpose,  mouth  upward,  from  the  water).  The  flame  is  at 
once  greatly  increased  in  brilliancy.  Now  remove  the  splinter  from  the 
bottle,  blow  out  the  flame,  and  thrust  the  still  glowing  point  into  the 
oxygen.  It  is  instantly  relighted.  The  experiment  mav  **>  repeated 
many  times.  This  is  the  usual  test  for  oxygen  gas. 

Combustion. — When  the  chemical  union  of  two  bodies 
takes  place  with  such  energy  as  to  produce  visible  phe 
nomena  of  fire  or  flame,  the  process  is  called  combustion. 
Bodies  that  burn  are  combustibles,  and  the  gas  in  which 
a  substance  burns  is  called  a  supporter  of  combustion. 

Oxygen  is  the  grand  supporter  of  combustion,  and  all 
the  cases  of  burning  met  with  in  ordinary  experience  are 
instances  of  chemical  union  between  the  oxygen  of  the  at 
mosphere  and  some  other  body  or  bodies. 

The  rapidity  or  intensity  of  combustion  depends  upon 
the  quantity  of  oxygen  and  of  the  combustible  that  unite 
within  a  given  time.  Forcing  a  stream  of  air  into  a  fire 
increases  the  supply  of  oxygen  and  excites  a  more  vigor 
ous  combustion,  whether  it  be  done  by  a  bellows  or  re 
sult  from  ordinary  draught. 

Oxygen  exists  in  our  atmosphere  to  the  extent  of  about 
one-fifth  of  the  bulk  of  the  latter.  When  a  burning  body 
is  brought  into  unmixed  oxygen,  its  combustion  is,  of 
course,  more  rapid  than  in  ordinary  air,  four-fifths  of 
which  is  a  gas,  presently  to  be  noticed,  that  is  nearly  in 
different  in  its  chemical  affinities  toward  most  bodies. 

In  the  air  a  piece  of  burning  charcoal  soon  goes  out ; 
but  if  plunged  into  oxygen,  it  burns  with  great  rapidity 
and  brilliancy. 

EXP.  6. — Attach  a  slender  bit  of  charcoal  to  one  end  of  a  sharpened 
wire  that  is  passed  through  a  wide  cork  or  card;  heat  the  charcoal  to 
redness  in  the  flame  of  a  lamp,  and  then  insert  it  into  a  bottle  of  oxygen, 


36 


HOW    CROPS    GROW. 


.  3. 


fig.  3.  When  the  combustion  has  declined,  a  suitable  test  applied  to  the 
air  of  the  bottle  will  demonstrate  that  another  invisible  gas  has  taken 
the  place  of  the  oxygen.  Such  a  test  is  lime-water.* 
On  pouring  some  of  this  into  the  bottle  and  agitating 
vigorously,  the  previously  clear  liquid  becomes  milky, 
and  on  standing,  a  white  deposit,  or  precipitate,  as  the 
chemist  terms  it,  gathers  at  the  bottom  of  the  vessel. 
Carbon,  by  thus  uniting  to  oxygen,  yields  carbonic  acid 
gas,  which  in  its  turn  combines  with  lime,  producing 
carbonate  of  lime.  These  substances  will  be  further 
noticed  in  a  subsequent  chapter. 

Metallic  iron  is  incombustible  in  the  at 
mosphere  under  ordinary  circumstances,  but 
if  heated  to  redness  and  brought  into  pure 
oxygen  gas,  it  burns  as  readily  as  wood  burns  in  the  air. 
EXP.  7. — Provide  a  thin  knitting  needle,  heat  one  end  red  hot,  and 
sharpen  it  by  means  of  a  file.  Thrust  the  point  thus 
made  into  a  splinter  of  wood,  (a  bit  of  the  stick  of  a 
match,  %  inch  long;)  pass  the  other  end  of  the  needle 
through  a  wide,  flat  cork  for  a  support,  set  the  wood  on 
fire,  and  immerse  the  needle  in  a  bottle  of  oxygen,  fig. 
4.  After  the  wood  consumes,  the  iron  itself  takes  fire 
and  burns  with  vivid  scintillations.  It  is  converted 
into  oxide  of  iron,  a  part  of  which  will  be  found  as  a 
yellowish-red  coating  on  the  sides  of  the  bottle;  the 
remainder  Avill  fuse  to  black,  brittle  globules,  which 
falling,  often  melt  quite  into  the  glass.  j?ig.  4. 

The  only  essential  difference  between  these  and  ordinary 
cases  of  combustion  is  the  intensity  with  which  the  pro 
cess  goes  on,  due  to  the  more  rapid  access  of  oxygen  to  the 
combustible. 

Many  bodies  unite  slowly  with  oxygen — oxidize,  as  it 
is  termed, — without  these  phenomena  of  light  and  intense 
heat  which  accompany  combustion.  Thus  iron  rusts,  lead 
tarnishes,  wood  decays.  All  these  processes  are  cases  of 
oxidation,  and  cannot  go  on  in  the  absence  of  oxygen. 

Since  the  action  of  oxygen  on  wood  and  other  organic 

*  To  prepare  lime-water,  put  a  piece  of  unslaked  lime,  as  large  as  a  chestnut, 
into  a  pint  of  water,  and  after  it  has  fallen  to  powder,  agitate  the  whole  for  a 
minute  in  a  well  stoppered  bottle.  On  standing,  the  excess  of  lime  will  settle, 
and  the  perfectly  clear  liquid  above  it  is  ready  for  use. 


\ 


THE   VOLATILE   FABT   OF   PLANTS.  3? 

matters  at  common  temperatures  is  strictly  analogous  in  a 
chemical  sense  to  actual  burning,. Liebig  has  proposed  the 
term  eremacausis,  (slow  burning),  to  designate  the  chemi 
cal  process  which  takes  place  in  decay  and  putrefaction, 
and  which  is  concerned  in  many  transformations,  as  in  the 
making  of  vinegar  and  the  formation  of  saltpeter. 

Oxygen  is  necessary  to  organic  life.  The  act  of  breath 
ing  introduces  it  into  the  lungs  and  blood  of  animals, 
where  it  aids  the  important  office  of  respiration.  Ani 
mals,  and  plants  as  well,  speedily  perish  if  deprived  of 
free  oxygen,  which  has  therefore  been  called  vital  air. 

Oxygen  has  a  universal  tendency  to  combine  with  other 
substances,  and  form  with  them  new  compounds.  With 
carbon,  as  we  have  seen,  it  forms  carbonic  acid.  With 
iron,  it  unites  in  various  proportions,  giving  origin  to  sev 
eral  distinct  oxides,  of  which  iron-rust  is  one,  and  anvil- 
scales  another.  In  decay,  putrefaction,  fermentation,  and 
respiration,  numberless  new  products  are  formed,  the  re 
sults  of  its  chemical  affinities. 

Oxygen  is  estimated  to  be  the  most  abundant  body  in 
nature.  In  the  free  state,  but  mixed  with  other  gases,  it 
of  the  bulk  of  the  atmosphere.  In 
chemical  union  with  otner  bodies,  it  forhlB  elifll L-Ilmllis  of 
the  weight  of  all  the  water  of  the  globe,  and  one-third  of 
its  solid  crust — its  soils  and  rocks, — as  well  as  of  all  the 
plants  and  animals  which  exist  upon  it.  In  fact  there  are 
but  few  compound  substances  occurring  in  ordinary  expe 
rience  into  which  oxygen  does  not  enter  as  a  necessary 
ingredient. 

Nitrogen. — This  body  is  the  other  chief  constituent  of 
the  atmosphere,  in  which  its  office  might  appear  to  be 
mainly  that  of  diluting  and  tempering  the  affinities  of 
oxygen.  Indirectly,  however,  it  serves  other  most  impor 
tant  uses,  as  will  presently  be  seen. 

For  the  preparation  of  nitrogen  we  have  only  to  remove 
the  oxygen  from  a  portion  of  atmospheric  air.  This  mav 


38  HOW    CROPS    GROW. 

be  accomplished  more  or  less  perfectly  by  a  variety  of 
methods.  We  have  just  learned  that  the  process  of  burn 
ing  is  a  chemical  union  of  oxygen  with  the  combustible. 
If,  now,  we  can  find  a  body  which  is  very  combustible  and 
one  which  at  the  same  time  yields  by  union  with  oxygen 
a  product  that  may  be  readily  removed  from  the  air  in 
which  it  is  formed,  the  preparation  of  nitrogen  from  ordi 
nary  air  becomes  easy.  Such  a  body  is  phosphorus,  a  / 
substance  to  be  noticed  in  some  detail  presently. 

EXP.  8. — The  bottom  of  a  dinner-plate  is  covered  half  an  inch  deep 
with  water,  a  bit  of  chalk  hollowed  out  into  a  little  cup  is  floated  on  the 
water  by  means  of  a  large  flat  cork  or  a  piece  of  wood ;  into  this  cup  a 
morsel  of  dry  phosphorus  as  large  as  a  pepper-corn  is 
placed,  which  is  then  set  on  fire  and  covered  by  a 
capacious  glass  bottle  or  bell  jar.  The  phosphorus 
burns  at  first  with  a  vivid  light,  which  is  presently  ob 
scured  by  a  cloud  of  snow-like  phosphoric  acid.  The 
combustion  goes  on,  however,  until  nearly  all  the  oxygen 
is  removed  from  the  included  air.  The  air  is  at  first  ex 
panded  by  the  heat  of  the  flame,  and  a  portion  of  it  es 
capes  from  the  vessel ;  afterward  it  diminishes  in  volume  T_.  „ 
as  its  oxygen  is  removed,  so  that  it  is  needful  to  pour 
water  on  the  plate  to  prevent  the  external  air  from  passing  into  the 
vessel.  After  some  time  the  white  fume  will  entirely  fall,  and  be  absorbed 
by  the  water,  leaving  the  inclosed  nitrogen  quite  clear. 

EXP.  9. — Another  instructive  method  of  preparing  nitrogen  is  the  fol 
lowing  :  A  handful  of  copperas  (sulphate  of  protoxide  of  iron)  is  dis 
solved  in  half  a  pint  of  water,  the  solution  is  put  into  a  quart  bottle,  a 
gill  of  liquid  ammonia  or  fresh  potash  lye  is  added,  the  bottle  stopper 
ed,  and  the  mixture  vigorously  agitated  for  some  minutes ;  the  stopper 
is  then  lifted,  to  allow  fresh  air  to  enter,  and  the  whole  is  again  agitated 
as  before;  this  is  repeated  occasionally  for  half  an  hour  or  more,  until 
no  further  absorption  takes  place,  when  nearly  pure  nitrogen  remains  in 
the  bottle. 

Free  nitrogen,  under  ordinary  circumstances,  has  scarce-     , 
ly  any  active  properties,  but  is  best  characterized  by  its    jS 
chemical  indifference  to  most  other  bodies.     That  it  is  in-    I 
capable  of  supporting  combustion  is  proved  by  the  first 
method  we  have  instanced  for  its  preparation. 

EXP.  10. — A  burning  splinter  is  immersed  iu  the  bottle  containing  the 
nitrogen  prepared  by  the  second  method,  Exp.  9 ;  the  flame  immediately 
goes  out. 


THE    VOLATILE    PART    OF    PLANTS.  39 

Nitrogen  cannot  maintain  respiration,  so  that  animals 
perish  if  confined  in  it.  For  this  reason  it  was  formerly 
called  Azote  (against  life).  Decay  does  not  proceed  in  an 
atmosphere  of  this  gas,  and  in  general  it  is  difficult  to  ef 
fect  its  direct  union  with  other  bodies.  At  a  high  tem 
perature,  especially  in  presence  of  baryta,  it  unites  with 
carbon,  forming  cyanogen-, — a  compound  existing  in  Prus 
sian-blue. 

The  atmosphere  is  the  great  store  and  source  of  nitrogen 
in  nature.  In  the  mineral  kingdom,  especially  in  soils, 
it  occurs  in  small  quantity  as  an  ingredient  of  saltpeter 
and  ammonia.  It  is  a  small  but  constant  constituent  of 
all  plants,  and  in  the  animal  it  is  a  never-failing  component 
of  the  working  tissues,  the  muscles,  tendons  and  nerves, 
and  is  hence  an  indispensable  ingredient  of  food. 

Hydrogen. — Water,  which  is  so  abundant  in  nature, 
and  so  essential  to  organic  existence,  is  a  compound  of 
two  elements,  viz. :  oxygen,  that  has  already  been  con 
sidered,  and  hydrogen,  which  we  now  come  to  notice. 

Hydrogen,  like  oxygen,  is  a  gas,  destitute,  when  pure, 
of  either  odor,  taste,  or  color.     It  does  not  occur  naturally 
in  the  free  state,  except  in  small  quantity  in  the  emana 
tions  from  boiling  springs  and  volcanoes.     Its  preparation 
almost  always  consists  in  abstracting  oxygen  from  water 
i  by  means  of  agents  which  have  no  special  affinity  for  hy- 
;  drogen,  and  therefore  leave  it  uncombined. 

Sodium,  a  metal  familiar  to  the  chemist,  has  such  an  at- 
i  traction  for  oxygen  that  it  decomposes  water  with  great 
rapidity. 

EXP.  11. — Hydrogen  is  therefore  readily  procured  by  inverting  a  bot 
tle  full  of  water  in  a  bowl,  and  inserting  into  it  a  bit  of  sodium  as  large 
as  a  pea.  The  sodium  must  first  be  wiped  free  from  the  naphtha  in 
which  it  is  kept,  and  then  be  wrapped  tightly  in  several  folds  of  paper. 
On  bringing  it,  thus  prepared,  under  the  mouth  of  the  bottle,  it  floats 
upward,  and  when  the  water  penetrates  the  paper,  an  abundant  escape 
of  gas  occurs. 

Metallic  iron  and  zinc  decompose  water,  uniting  with 


40 


HOW    CROPS    GROW. 


oxygen  and  setting  hydrogen  free.  This  action  is  almost 
imperceptible,  however,  with  pure  water  under  ordinary 
circumstances,  because  the  metals  are  soon  coated  with  a 
film  of  oxide  which  prevents  further  contact.  If  to  the 
water  a  strong  acid  be  added,  or,  in  case  zinc  is  used,  an 
alkali,  the  production  of  hydrogen  goes  on  very  rapidly, 
because  the  oxide  is  dissolved  as  fast  as  it  forms,  and  a 
perfectly  pure  metallic  surface  is  constantly  presented  to 
the  water. 

EXP.  12.— Into  a  bottle  fitted  with  cork,  funnel,  and  delivery  tubes, 
fig.  6,  an  ounce  of  iron  tacks 
or  zinc  clippings  is  introduced, 
a  gill  of  water  is  poured  upon 
them,  and  lastly  an  ounce  of 
oil  of  vitriol  is  added.  A  brisk 
effervescence  shortly  com 
mences,  owing  to  the  escape 
of  nearly  pure  hydrogen  gas, 
which  may  be  collected  in  a 
bottle  filled  with  water  as 
directed  for  oxygen.  The 
first  portions  that  pass  over 
are  mixed  with  air,  and  should 
be  rejected,  as  the  mixture  is 
dangerously  explosive. 

One  of  the  most  strik- 
ing    properties  of    free 

hydrogen  is  its  levity.  It  is  the  lightest  body  in  nature, 
being  fourteen  and  a  half  times  lighter  than  common  air. 
It  is  hence  used  in  filling  balloons. 
Another  property  is  its  combustibili 
ty  ;  it  inflames  on  contact  with  a 
lighted  taper,  and  burns  with  a  flame 
which  is  intensely  hot,  though  scarce 
ly  luminous  if  the  gas  be  pure.  Final 
ly,  it  is  itself  incapable  of  support 
ing  the  combustion  of  a  taper. 

EXP.  13.— All  these  characters  may  be  shown  by  the  following  single 
experiment.  A  bottle  full  of  hydrogen  is  lifted  from  the  water  over 
which  it  has  been  collected,  and  a  taper  attached  to  a  bent  wire,  fig.  7,  is 


Fig.  7. 


THE    VOLATILE   PART    OF   PLANTS.  41 

brought  to  its  mouth.  At  first  a  slight  explosion  is  heard  from  the  sudden 
burning  of  a  mixture  of  the  gas  with  air  that  forms  at  the  mouth  of  the 
vessel ;  then  the  gas  is  seen  burning  on  its  lower  surface  with  a  pale  flame. 
If  now  the  taper  be  passed  into  the  bottle  it  will  be  extinguished ;  on  low 
ering  it  again,  it  will  be  relighted  by  the  burning  gas;  finally,  if  the  bot 
tle  be  suddenly  turned  mouth  upwards,  the  light  hydrogen  rises  in  a 
sheet  of  flame. 

In  the  above  experiment,  the  hydrogen  burns  only  where 
it  is  in  contact  with  atmospheric  oxygen ;  the  product  of 
the  combustion  is  an  oxide  of  hydrogen,  the  universally  dif 
fused  compound,  water.  The  conditions  of  the  experiment 
do  not  permit  the  collection  or  identification  of  this  wa 
ter  ;  its  production  can,  however,  readily  be  demon 
strated. 

EXP.  14. — The  arrangement  shown  in  fig.  8  may  be  employed  to  ex 
hibit  the  formation  of  water  by  the  burning  of  hydrogen.  Hydrogen 
gas  is  generated  from  zinc  and  dilute  acid  in  the  two-necked  bottle. 
Thus  produced,  it  is  mingled  with  vapor  of  water,  to  remove  which  it 


Fig,  8. 


is  made  to  stream  slowly  through  a  wide  tube  filled  with  fragments  of 
dried  chloride  of  calcium,  which  desiccates  it  perfectly.  After  air  has 
been  entirely  displaced  from  the  apparatus,  the  gas  is  ignited  at  the  up- 
curved  end  of  the  narrow  tube,  and  a  clean  bell-glass  is  supported  over 
the  flame.  Water  collects  at  once,  as  dew,  on  the  interior  of  the  bell, 
and  shortly  flows  down  in  drops  into  a  vessel  placed  beneath. 

In  the  mineral  world  we  scarcely  find  hydrogen  occur- 
ijj  ring  in  much  quantity,  save  as  water.     It  is  a  constant  in 
gredient  of  plants  and  animals,  and  of  nearly  all   the 
numberless  substances  which  are  products  of  organic  life. 


42  HOW   CROPS    GROW. 

Hydrogen  forms  with  carbon  a  large  number  of  com 
pounds,  the  most  common  of  which  are  the  volatile  oils, 
like  oil  of  turpentine,  oil  of  lemon,  etc.  The  chief  illumi 
nating  ingredient  of  coal-gas  (ethylene  or  olefiant  gas,) 
the  coal  or  rock  oils,  (kerosene,)  together  with  benzine 
and  paraffine,  are  so-called  hydro-carbons. 

Sulphur  is  a  well-known  solid  substance,  occurring  in 
commerce  either  in  sticks  (brimstone,  roll  sulphur,)  or  as 
a  fine  powder  (flowers  of  sulphur),  having  a  pale  yellow 
color,  and  a  peculiar  odor  and  taste. 

Uncombined  sulphur  is  comparatively  rare,  the  com 
mercial  supplies  being  almost  exclusively  of  volcanic  ori 
gin  ;  but  in  one  or  other  form  of  combination,  this  element 
is  universally  diffused. 

Sulphur  is  combustible.  It  burns  in  the  air  with  a  pale 
blue  flame,  in  oxygen  gas  with  a  beautiful  purple-blue  flame, 
yielding  in  both  cases  a  suffocating  and  fuming  gas  of 
peculiar  nauseous  taste,  which  is  called  sulphurous  acid. 

EXP.  15. — Heat  a  bit  of  sulphur  as  lar^e  as  a  grain  of  wheat  on  a  slip 
of  iron  or  glass,  in  the  flame  of  a  spirit  lamp,  for  observing  its  fusion, 
combustion,  and  the  development  of  sulphurous  acid.  Furl  her,  scoop 
out  a  little  hollow  in  a  piece  of  chalk,  twist  a  wire  around  the  latter  to 
serve  for  a  handle,  as  in  fig.  3 ;  heat  the  chalk  with  a  fragment  of  sulphur 
upon  it  until  the  latter  ignites,  and  bring  it  into  a  bottle  of  oxygen  gas. 
The  purple  flame  is  shortly  obscured  by  the  opaque  white  fume  of  the 
^ulphurous  acid. 

Sulphur  forms  with  oxygen  another  compound,  which, 
in  combination  with  water,  constitutes  common  sulphuric 
acid,  or  oil  of  vitriol.  This  is  developed  to  a  slight  ex 
tent  by  the  action  of  air  on  flowers  of  sulphur,  but  is  pre 
pared  on  a  large  scale  for  commerce  by  a  complicated 
process. 

Sulphur  unites  with  most  of  the  metals,  yielding  com 
pounds  known  as  sulphides  or  sulphurets.  These  exist  in 
nature  in  large  quantities,  especially  the  sulphides  of  iron, 
copper,  and  lead,  and  many  of  them  are  valuable  ores. 


I 


THE  VOLATILE  PART  OF  PLANTS.  43 

Sulphides  may  be  formed  artificially  by  heating  most  of 
the  metals  with  sulphur. 

EXP.  16.  —  Heat  the  bowl  of  a  tobacco  pipe  to  a  low  red  heat  in  a  stove 
or  furnace;  have  in  readiness  a  thin  iron  wire  or  watch-spring  made  into 
a  spiral  coil  ;  throw  into  the  pipe-bowl  some  lumps  of  sulphur,  and  when 
these  melt  and  boil  with  formation  of  a  red  vapor  or  gas,  introduce  the 
iron  coil,  previously  heated  to  redness,  into  the  sulphur  vapor.  The 
eulphur  and  iron  unite;  the  iron,  in  fact,  burns  in  the  sulphur  gas,  giv 
ing  rise  to  a  black  sulphide  of  iron,  in  the  same  manner  as  in  Exp.  7  it 
ourned  in  oxygen  gas  and  produced  an  oxide  of  iron.  The  sulphide  of 
iron  melts  to  brittle,  round  globules,  and  remains  in  the  pipe-bowl. 

With  hydrogen,  the  element  we  are  now  considering 
unites  to  form  a  gas  that  possesses  in  a  high  degree  the 
odor  of  rotten  eggs,  which  is,  in  fact,  the  chief  cause  of 
the  noisomeness  of  this  kind  of  putridity.  This  substance, 
commonly  called  sulphuretted  hydrogen,  also  sulphydric 
acid,  is  dissolved  in,  and  evolved  abundantly  from,  the 
water  of  sulphur  springs.  It  may  be  produced  artificially 
by  acting  on  some  metallic  sulphides  with  dilute  sulphuric 
acid. 

EXP.  17.  —  Place  a  lump  of  the  sulphide  of  iron  prepared  in  Exp.  16  in 
a  cup  or  wine-glass,  add  a  IHtle  water,  and  lastly  a  few  drops  of  oil  of 
vitriol  Bubbles  of  sulphuretted  hydrogen  gas  will  shortly  escape. 

In  soils,  sulphur  occurs  almost  invariably  in  the  form 
of  sulphates,  compounds  of  sulphuric  acid  with  metals, 
a  class  of  bodies  to  be  hereafter  noticed. 

In  plants,  sulphur  is  always  present,  though  usually  in 
small  quantity.  The  turnip,  the  onion,  mustard,  horse 
radish,  and  assafoetida,  owe  their  peculiar  flavors  to  volatile 
oils  in  which  sulphur  is  an  ingredient. 

Albumin,  gluten  and  casein,  —  vegetable  principles  never 
absent  from  plant  or  animal,  —  possess  also  a  small  content 
of  sulphur.  In  hair  and  horn  it  occurs  to  the  amount  of 
3  to  5  per  cent. 

When  organic  matters  are  burned  with  full  access  of      i 
air,  their  sulphur  is  oxidized  and  remains  in  the  ash  as      > 


sulphuric  acid,  or  escapes  into  the  air  as  sulphurous 

Phosphorus  is  an  element  which  has  such  intense  a£ 


44  HOW   CROPS    GROW. 

Unities  for  oxygen  that  it  never  occurs  naturally  in  the 
free  state,  and  when  prepared  by  art,  is  usually  obliged  to 
be  kept  immersed  in  water  to  prevent  its  oxidizing,  or 
even  taking  fire.  It  is  known  to  the  chemist  in  the  solid 
state  in  two  distinct  forms.  In  the  more  commonly  occur 
ring  form,  it  is  colorless  or  yellow,  translucent,  wax-like  in 
appearance ;  is  intensely  poisonous,  inflames  by  moderate 
friction,  and  is  luminous  in  the  dark,  hence  its  name,  de 
rived  from  two  Greek  words  signifying  light-bearer.  The 
other  form  is  brick  red,  opaque,  far  less  inflammable,  and 
destitute  of  poisonous  properties.  Phosphorus  is  exten 
sively  employed  for  the  manufacture  of  friction  matches. 
For  this  purpose  yellow  phosphorus  is  chiefly  used. 

When  exposed  sufficiently  long  to  the  air,  or  immedi- 
1  J  ately,  on  burning,  this  element  unites  with  oxygen,  form- 
j    ing  a  body  of  the  utmost  agricultural  importance,  viz. . 
|  phosphoric  acid. 

EXP.  18. — Burn  a  bit  of  phosphorus  under  a  bottle  as  in  Exp.  8,  omit 
ting  the  water  on  the  plate.  The  snow-like  cloud  of  phosphoric  acid 
gathers  partly  on  the  sides  of  the  bottle,  but  mostly  on  the  plate.  It 
attracts  moisture  when  exposed  to  the  air,  and  hisses  when  put  into  wa 
ter.  Dissolve  a  portion  of  it  in  water,  and  observe  that  the  solution  ia 
acid  to  the  taste. 

/   In  nature  phosphorus  is  usually  found  in  the  form  of 
(  phosphates,  which  are  compounds  of  metals  with  phos 
phoric  acid. 

In  plants  and  animals,  it  exists  for  the  most  part  as 
phosphates  of  lime,  magnesia,  potash,  and  soda. 

The  bones  of  animals  contain  a  considerable  proportion 
(10  per  cent)  of  phosphorus  mainly  in  the  form  of  phos 
phate  of  lime.  It  is.  from  them  that  the  phosphorus  em 
ployed  for  matches  is  largely  procured. 

EXP.  19. — Burn  a  piece  of  bone  in  a  fire  nntil  it  becomes  white,  or 
nearly  so.  The  bone  lo?es  about  half  its  weight.  What  remains  ia 
bone-earth  or  bone-ash,  and  of  this  90  per  cent  is  phosphate  of  lime. 

Phosphates  are  readily  formed  by  bringing  together  so 
lutions  of  various  metals  with  solution  of  phosphoric  acid. 

RXP.  20.— Pour  into  each  of  two  wine  or  test  glasses  a  small  quantity 


THE  VOLATILE  PART  OF  PLANTS.  4,5 

nf  the  solution  of  phosphoric  acid  obtained  in  Exp.  18.  To  one,  add 
some  lime-water  (see  note  p.  36)  until  a  white  cloud  or  precipitate  is  per 
ceived.  This  is  a  phosphate  of  lime.  Into  the  other  portion,  drop  solu 
tion  of  alum.  A  translucent  cloud  of  phosphate  of  alumina  is  immediately 
produced. 

In  soils  and  rocks,  phosphorus  exists  in  the  state  of 
such  phosphates  of  lime,  alumina,  and  iron. 

In  the  organic  world  the  chemist  has  as  yet  detected 
phosphorus  in  other  states  of  combination  in  but  a  few 
instances.  In  the  brain  and  nerves,  and  in  the  yolk  of 
eggs,  an  oil  containing  phosphorus  has  been  known  for 
some  years,  and  recently  similar  phosphorized  oils  have 
been  found  in  the  pea,  in  maize,  and  other  grains. 

We  have  thus  briefly  noticed  the  more  important  char 
acters  of  those  six  bodies  which  constitute  that  part  of 
plants,  and  of  animals  also,  which  is  volatile  or  destruct 
ible  at  high  temperatures,  viz. :  carbon,  hydrogen,  oxygen, 
nitrogen,  sulphur,  and  phosphorus. 

Out  of  these  substances  chiefly,  which  are  often  termed 
the  organic  elements  of  vegetation,  are  compounded  all 
the  numberless  products  of  life  to  be  met  with,  either  in 
the  vegetable  or  animal  world. 

ULTIMATE   COMPOSITION   OF   VEGETABLE   MATTER. 

To  convey  an  idea  of  the  relative  proportions  in  which 
these  six  elements  exist  in  plants,  a  statement  of  the 
ultimate  or  elementary  percentage  composition  of  several 
kinds  of  vegetable  matter  is  here  subjoined. 

Grain  of  Straio  of  Tubers  of  Grain  of  Hay  of  Red 

Wheat.  Wheat.  Potato.  Peas.  Clover. 

Carbon 46.1  48.4  44.0  46.5  47.4 

Hydrogen 5.8  5.3  5.8  6.2  5.0 

Oxygen 43.4  38.9  44.7  40.0  37.8 

Nitrogen 2.3  0.4  1.5  4.2  2.1 

Ash,  including  sulphur    )  2  4  ?()  4Q  gl  ?7 
and  phosphorus         J  *•*  . 

100.0         100.0         100.0         ',00.0         100.0 

Sulphur 0.12  0.14  0.08  0.21  0.18 

Phosphorus 0.30  0.80  0.34  0.34  0.20 


46  HOW   CROPS   GROW. 

Our  attention  may  now  be  directed  to  the  study 
compounds  of  these  elements  as  constitute  the  basis  of 
plants  in  general ;  since  a  knowledge  of  them  will  prepare 
us  to  consider  the  remaining  elements  with  a  greater  de 
gree  of  interest. 

Previous  to  this,  however,  we  must,  first  of  all,  gain  a 
clear  idea  of  that  force  or  energy,  in  virtue  of  whose  action, 
chiefly,  these  elements  are  held  in,  or  separated  from  their 
combinations. 

§3.  ,    ':  : 

CHEMICAL    AFFINITY. 

Chemical  attraction  or  affinity  is  the  force  which  unites 
or  combines  two  or  more  substances  of  unlike  character,  to 
a  new  body  different  from  its  ingredients. 

Chemical  combination  differs  essentially  from  mere  mix* 
ture.  Thus  we  may  mix  together  in  a  vessel  the  two  gases 
oxygen  and  hydrogen,  and  they  will  remain  uncombined 
for  an  indefinite  time,  occupying  their  original  volume ; 
but  if  a  flame  be  brought  into  the  mixture  they  instantly 
unite  with  a  loud  explosion,  and  in  place  of  the  light  and 
bulky  gases,  we  find  a  few  drops  of  water,  which  is  a  liquid 
at  ordinary  temperatures,  and  in  winter  weather  becomes 
solid,  which  does  not  sustain  combustion  like  oxygen,  nor 
itself  bum  as  does  hydrogen ;  but  is  a  substance  having  its 
own  peculiar  properties,  differing  from  those  of  all  other 
bodies  with  which  we  are  acquainted. 

In  the  atmosphere  we  have  oxygen  and  nitrogen  in  a 
state  of  mere  mixture,  each  of  these  gases  exhibiting  its 
own  characteristic  properties  When  brought  into  chemi 
cal  combination,  they  are  capable  of  yielding  a  series  of 
no  less  than  five  distinct  compounds,  one  of  which  is  the 
so-called  laughing  gas,  while  the  others  form  suffocating 
and  corrosive  vapors  that  are  totally  irrespirable. 


THE    VOLATILE    PART    OF   PLANTS.  47 

Chemical  decomposition. — Water,  thus  composed  or 
put  together  by  the  exercise  of  affinity,  is  easily  decom« 
posed  or  taken  to  pieces,  so  to  speak,  by  forces  that  op 
pose  affinity — e.  g.,  heat  and  electricity — or  by  the  greater 
affinity  of  some  other  body — e.  g.,  sodium — as  already 
illustrated  in  the  preparation  of  hydrogen,  Exp.  11. 

Definite  proportions, — A  further  distinction  between 
chemical  union  and  mere  mixture  is,  that,  while  two  or 
more  bodies  may,  in  general,  be  mixed  in  all  proportions, 
bodies  combine  chemically  in  comparatively  few  propor 
tions,  which  are  fixed  and  invariable.  Oxygen  and  hydro 
gen,  e.  g.,  are  found  united  in  nature,  principally  in  the 
form  of  water ;  and  water,  if  pure,  is  always  composed  of 
exactly  one-ninth  hydrogen  and  eight-ninths  oxygen  by 
weight,  or,  since  oxygen  is  sixteen  times  heavier  than 
hydrogen,  bulk  for  bulk,  of  one  volume  or  measure  of 
oxygen  to  two  volumes  of  hydrogen. 

Atomic  Weight  of  Elements. — On  the  hypothesis 
that  chemical  union  takes  place  between  atoms  or  indi 
visible  particles  of  the  elements,  the  numbers  expressing 
the  proportions  by  weight*  in  which  they  combine,  are 
appropriately  termed  atomic  iceights.  These  numbers  are 
only  relative,  and  since  hydrogen  is  the  element  which 
unites  in  the  smallest  proportion  by  weight,  it  is  assumed 
as  the  standard.  From  the  results  of  a  great  number  of 
the  most  exact  experiments,  chemists  have  generally  agreed 
upon  the  atomic  weights  given  in  the  subjoined  table  for 
the  elements  already  mentioned  or  described. 

Symbols, — For  convenience  in  representing  chemical 
changes,  the  first  letter,  (or  letters,)  of  the  Latin  name  of 
the  element  is  employed  instead  of  the  name  itself,  and  is 
termed  its  symbol. 


*  Unless  otherwise  stated,  parts  or  proportions  by  weight  are  always  to  b« 
understood. 


48  HOW  CROPS   GROW 

TABLE    OP    ATOMIC  WEIGHTS    AND   SYMBOLS   OF    ELEMENTS.* 

Element.  At.  wt.        Symbol. 

Hydrogen  1  H 

Carbon  12  C 

Oxygen  16  O 

Nitrogen  14  N 

Sulphur  32  S 

Phosphorus  31  P 

Chlorine  35.5  Cl 

Mercury  200  Hg  (Hydrargyrum) 

Potassium  39  K    (Kalium) 

Sodium  23  Na  (Natrium) 

Calcium  40  Ca 

Iron  56  Fe  (Ferrum) 

Multiple  Proportions. — When  two  or  more  bodies  unite 
in  several  proportions,  their  quantities,  when  not  expressed 
by  the  atomic  weights,  are  twice,  thrice,  four,  or  more  times, 
these  weights ;  they  are  multiples  of  the  atomic  weights  by 
some  simple  number.  Thus,  carbon  and  oxygen  form  two 
commonly  occurring  compounds,  viz.,  carbonic  oxide,  con 
sisting  of  one  atom  of  each  ingredient,  and  carbonic  acidf 
which  contains  to  one  atom,  or  12  parts  by  weight,  of  car 
bon,  two  atoms,  or  32  parts  by  weight,  of  oxygen. 

Molecular  Weights  of  Compounds. — While  elements 
unite  by  indivisible  atoms,  to  form  compounds,  the 
compounds  themselves  combine  with  each  other,  or 
exist  as  molecules ,f  or  aggregations  of  atoms.  It  has 
indeed  been  customary  to  speak  of  atoms  of  a  com 
pound  body,  but  this  is  an  absurdity,  for  the  smallest  par 
ticles  of  compounds  admit  of  separation  into  their  elements. 
The  term  molecule  implies  capacity  for  division  just  as 
atom  excludes  that  idea. 

*  Latterly,  chemists  are  mostly  inclined  to  receive  as  the  true  atomic  weighti 
double  the  numbers  that  have  been  commonly  employed,  hydrogen,  chlorine 
and  a  few  others  excepted. 

+  Latin  diminutive,  signifying  a  little  mast. 


THE  VOLATILE   PART   OP  PLANTS.  49 

The  molecular  weight  of  a  compound  is  the  sum  of  the 
weights  of  the  atoms  that  compose  it.  For  example,  wa 
ter  being  composed  of  1  atom,  or  16  parts  by  weight,  of 
oxygen,  and  2  atoms,  or  2  parts  by  weight,  of  hydrogen, 
has  the  molecular  weight  of  18. 

The  following  scheme  illustrates  the  molecular  compo 
sition  of  a  somewhat  complex  compound,  one  of  the  car 
bonates  of  ammonia. 

Ammonia  gas  results  from  the  union  of  an  atom  of 
nitrogen  with  three  atoms  of  hydrogen.  One  molecule 
of  ammonia  gas  unites  with  a  molecule  of  carbonic  acid 
gas  and  a  molecule  of  water,  to  produce  a  molecule  of 
carbonate  of  ammonia. 


Carbonate 

of  1  mol  .=• 
Ammonia 


f  Ammonia 

1  mol. "~ 
Carbonic  acid, 
1  mol.  — 


Hydrogen,  3  ats.  = 
Nitrogen,  1    ' 
Carbon,      1 
Oxygen, 


Water,  =  J  Hydrogen,  2 

1  mol.  =  j  Oxygen,     1 


Notation  Of  Compounds. — For  the  purpose  o^express- 
ing  easily  and  concisely  the  composition  of  compounds, 
and  the  chemical  changes  they  undergo,  chemists  have 
agreed  to  make  the  symbol  of  an  element  signify  one  atom 
of  that  element. 

Thus  H  implies  not  only  the  light,  combustible  gas  hy 
drogen,  but  one  part  of  it  by  weight  as  compared  with  other 
elements,  and  S  suggests,  in  addition  to  the  idea  of  the 
body  sulphur,  the  idea  of  32  parts  of  it  by  weight.  Through 
this  association  of  the  atomic  weight  with  the  symbol,  the 
composition  of  compounds  is  expressed  in  the  simplest 
.manner  by  writing  the  symbols  of  its  elements  one  after 
the  other,  thus:  carbonic  oxide  is  represented  by  C  O, 
oxide  of  mercury  by  Hg  O,  and  sulphide  of  iron  by  Fe  S. 
C  O  conveys  to  the  chemist  not  only  the  fact  of  the 
existence  of  carbonic  oxide,  but  also  instructs  him  that  its 
molecule  contains  an  atom  each  of  carbon  and  of  oxygen, 
and  from  his  knowledge  of  the  atomic  weights  he  gathers 
the  proportions  by  weight  of  the  carbon  and  oxygen  in  it 


60  HOW    CROPS    GROW. 

When  a  compound  contains  more  than  one  atom  ot  da 
element,  this  is  shown  by  appending  a  small  figure  to  the 
symbol  of  the  latter.  For  example :  water  consists  of 
two  atoms  of  hydrogen  united  to  one  of  oxygen,  the 
symbol  of  water  is  then  H2  O.  In  like  manner  the  symbol 
of  carbonic  acid  is  C  O2. 

When  it  is  wished  to  indicate  that  more  than  one  mole- 
cule  of  a  compound  exists  in  combination  or  is  concerned 
in  a  chemical  change,  this  is  done  by  prefixing  a  large 
figure  to  the  symbol  of  the  compound.  For  instance, 
two  molecules  of  water  are  expressed  by  2  H2  Q. 

The  symbol  of  a  compound  is  usually  termed  &  formula* 
Subjoined  is  a  table  of  the  formulas  of  some  of  the  com 
pounds  that  have  been  already  described  or  employed. 

FORMULAS    OF   COMPOUNDS. 

N"ame.  Formula,.  Molecular  weigh*,. 

Water  H2  O  18 

Sulphydric  acid  H2  S  34 

Sulphide  of  iron  Fe  S  88 

Oxide  of  Mercury  Hg  O  216 

Carbonic  acid  (anhydrous)  C  O2  44 

Chloride  of  calcium"  Ca  C13  111 

Sulphurous  acid  (anhydrous)       S  O2  64 

Sulphuric  acid  S  O3  80 

Phosphoric  acid  P2  O5  142 

Empirical  and  Rational  Formulas, — It  is  obvious  that 
many  different  formulas  can  be  made  for  a  body  of  com 
plex  character.  Thus,  the  carbonate  of  ammonia,  whoso 
composition  has  already  been  stated,  (p.  49,)  and  which 

contains 

1  atom  of  Nitrogen, 

1      "       "  Carbon, 

3  atoms  "  Oxygen,  and 

5     "       "  Hydrogen, 

may  be  most  compactly  expressed  by  the  symbol 
N  C  O,  H6. 


THE  VOLATILE  PART  OF  PLANTS.  51 

Such  a  formula  merely  informs  us  what  elements  and 
fiow  many  atoms  of  each  element  enter  into  the  composi 
tion  of  the  substance.  It  is  an  empirical  formula,  being 
the  simplest  expression  of  the  facts  obtained  by  analysis 
of  the  substance. 

Rational  formulas,  on  the  other  hand,  are  intended  to 
convey  some  notion  as  to  the  constitution,  formation,  or 
modes  of  decomposition  of  the  body.  For  example,  the 
fact  that  carbonate  of  ammonia  results  from  the  union 
of  one  molecule  each  of  carbonic  acid,  water,  and  ammonia, 
is  expressed  by  the  formula 

N  H.,  H,  O,  C  O,. 

A  substance  may  have  as  many  rational  formulas  as 
there  are  rational  modes  of  viewing  its  constitution. 

Equations  Of  Formulas  serve  to  explain  the  results  of 
chemical  reactions  and  changes.  Thus  the  breaking  up 
by  heat  of  chlorate  of  potash  into  chloride  of  potassium 
and  oxygen,  is  expressed  by  the  following  statement. 
Chlorate,  of  potash.  Chloride  of  potassium.  Oxygen. 
K  Cl  O?  K  Cl  +  O3 

The  sign  of  equality.  =,  shows  that  what  is  written  be 
fore  it  supplies,  and  is  resolved  into  what  follows  it.  The 
sign  +  indicates  and  distinguishes  separate  compounds. 

The  employment  of  this  kind  of  short-hand  for  exhibit 
ing  chemical  changes  will  find  frequent  illustration  as  we 
proceed  with  our  subject. 

Modes  of  Statin?  Composition  of  Chemical  Compounds. 

— These  are  two,  viz.,  atomic  or  molecular  statements  and 
centesimal  statements,  or  proportions  in  one  hundred  parts, 
(per  cent,  p,  c.  or  °|0.)  These  modes  of  expressing  com 
position  are  very  useful  for  comparing  together  different 
compounds  of  the  same  elements,  and,  while  usually  the 
atomic  statement  answers  for  substances  which  are  com 
paratively  simple  in  their  composition,  the  statement  per 
cent  is  more  useful  for  complex  bodies.  The  composition 


52  HOW   CROPS    GROW. 

of  the  two  compounds  of  carbon  with  oxygen  is  given  be 
low  according  to  both  methods. 

Atomic.  Per  cent.  Atomic.  Per  cent. 

Carbon,  (C,)  12        42.86      (C)  12        27.27 

Oxygen,  (O,)  16       57.14      (02)  32       72.73 

Carbonic  oxide,  (C  O,)  28      100.00      Carbonic  acid,  (C  O2,)  44      100.00 

The  conversion  of  dne  of  these  statements  into  the  other  is  a  case  of 
simple  rule  of  three,  which  is  illustrated  iu  the  following  calculation  of 
the  centesim/il  compositior  of  water  from  its  atomic  formula. 

Water,  H2  O,  has  the  molecular  weight  18,  i.  e.,  it  consists  of  two 
atoms  of  hydrogen,  or  two  parts,  and  one  atom  of  oxygen,  or  sixteen 
parts  by  weight. 

The  arithmetical  proportions  subjoined  serve  for  the  calculation,  viz.: 

H2  O  Water  H  Hydrogen 

18       :        100  :  :  2       :        per  cent  sought  (  — 11. 11  +  ) 

H20  Water  O  Oxygen 

18       :        100  ::  16      :        per  cent  sought  («- 88.88  +  ) 

By  multiplying  together  the  second  and  third  terms  of  these  propor 
tions,  and  dividing  by  the  first,  we  obtain  the  required  per  cent,  viz.,  of 
hydrogen,  11.11;  and  of  oxygen,  88.88. 

The  reader  must  bear  well  in  mind  that  chemical  affinity 
manifests  itself  with  very  different  degrees  of  intensity 
between  different  bodies,  and  is  variously  modified,  excited, 
or  annulled,  by  other  natural  agencies  and  forces. 

Q  4. 

VEGETABLE    ORGANIC    COMPOUNDS    OR    PROXIMATE 
ELEMENTS. 

We  are  now  prepared  to  enter  upon  the  study  of  the 
organic  compounds,  which  constitute  the  vegetable  struc 
ture,  and  which  are  produced  from  the  elements  carbon, 
oxygen,  hydrogen,  nitrogen,  sulphur,  and  phosphorus,  by 
the  united  agency  of  chemical  and  vital  forces.  The  num 
ber  of  distinct  substances  found  in  plants  is  practically  un 
limited.  There  are  already  well  known  to  chemists  hun 
dreds  of  oils,  acids,  bitter  principles,  resins,  coloring  mat 
ters,  etc.  Almost  every  plant  contains  some  organic  body 


o  ^  \<F 

(y^L 

THE  VOLATILE  PAKT  OF  PLANTS.  .r)3 

peculiar  to  itself,  and  usually  the  same  plant  in  its  different 
parts  reveals  to  the  senses  of  taste  and  smell  the  presence 
of  several  individual  substances.  In  tea  and  coffee  occurs 
an  intensely  bitter  "  active  principle,"  them.  From  tobacco 
an  oily  liquid  of  eminently  narcotic  and  poisonous  proper 
ties,  nicotin,  can  be  extracted.  In  the  orange  are  found 
no  less  than  three  oils  ;  one  in  the  leaves,  one  in  the  flow 
ers,  and  a  third  in  the  rind  of  the  fruit. 

Notwithstanding  the  great  number  of  bodies  thus  occur- 
ing  in  the  vegetable  kingdom,  it  is  a  few  which  form  the 
bulk  of  all  plants,  and  especially  of  those  which  have  an  agri 
cultural  importance  as  sources  of  food  to  man  and  animals. 
These  substances,  into  which  any  plant  may  be  resolved  by 
simple,  mostly  mechanical  means,  are  conveniently  termed 
proxhnate-ilementS)  and  we  shall  notice  them  in  some  de 
tail  under  six  principal  groups,  viz  : 

1.  WATER. 

2.  The  CELLULOSE   GROUP    OR    AMYLOIDS — Cellulose, 
d,)  Starch,  the  Sugars  and  Gums. 

3.  The  PECTOSE  GROUP — the  Pulp  and  Jellies  of  Fruits 
certain  Roots. 

4.  The  VEGETABLE  ACIDS. 

5.  The  FATS  and  OILS. 

•^6.  The  ALBUMINOID  or  PROTEIN  BODIES^ 

1.  Water,  Ha  O,  as  already  stated,  is  the  most  abundant 
ingredient  of  plants.  It  is  itself  a  compound  of  oxygen  and 
hydrogen,  having  the  folio  wing -centesimal  composition: 
Oxygen,         88.88 
Hydrogen,    11.11 

.      100.00 

It  exists  in  all  parts  of  the  plant,  is  the  immediate  cause 
of  the  succulence  of  the  tender  parts,  and  is  essential  to 
the  life  of  the  vegetable  organs. 

In  the  following  table  are  given  the  percentages  of  water  in  some  of 
the  more  common  agricultural  products  in  the/res7i  date,  but  the  pro> 


54  now  CROPS  GROW. 

portions  are  not  quite  constant,  even  in  the  same  part  of  different  speci 
mens  of  any  given  plant. 

WATER  (per  cent)  IN  FKESH  PLANTS. 

Meadow  grass 72 

Red  clover 79 

Maize,  as  used  for  fodder 81 

Cabbage 90 

Potato  tubers 75 

Sugar  beets 82 

Carrots 85 

Turnips 91 

Pine  wood ". 40 

*y 

In  living  plants,  water  is  usually  perceptible  to  the  eye 
or  feel,  as  sap.  But  it  is  not  only  fresh  plants  that  con 
tain  water.  When  grass  is  made  into  hay,  the  water  is  by 
no  means  all  dried  out,  but  a  considerable  proportion  re 
mains  in  the  pores,  which  is  not  recognizable  by  the 
senses.  So,  too,  seasoned  wood,  flour,  and  starch,  when 
seemingly  dry,  contain  a  quantity  of  invisible  water,  which 
can  be  removed  by  heat. 

EXP.  21.— Into  a  wide  glass  tube,  like  that  shown  in  fig.  2,  place  a 
spoonful  of  saw-dust,  or  starch,  or  a  little  hay.  Warm  over  a  lamp,  but 
very  slowly  and  cautiously,  so  as  not  to  burn  or  blacken  the  substance. 
Water  will  be  expelled  from  the  organic  matter,  and  will  collect  on  the 
cold  part  of  the  tube. 

It  is  thus  obvious  that  vegetable  substances  may  con 
tain  water  in  two  different  conditions.     Red  clover,  for 
example,   when  growing  or  freshly   cut, 
contains  about    79    per   cent  of    water. 
When  the  clover  is  dried,  as  for  making 
hay,  the  greater  share  of  this  water  es 
capes,  so  that  the  air-dry  plant  contains 
but  about  17  per  cent.     On  subjecting  the 
air-dry  clover  to  a  temperature  of  212° 
for  some  hours,  the  water  is  completely  expelled,  and  the 
substance  becomes  really  dry. 

To  drive  off  all  water  from  vegetable  matters,  the  chemist  usually  em 
ploys  a  water-bath,  fig.  9,  consisting  of  a  vessel  of  tin  or  copper  plate, 
with  double  walls,  between  which  is  a  space  that  may  be  nearly  filled 
with  water.  The  substance  to  be  dried  is  placed  in  the  interior  chamber, 


THE  VOLATILE  PART  OF  PLANTS.  55 

the  door  is  closed,  and  the  water  is  brought  to  boil  by  the  heat  of  a  lamp 
or  stove.  The  precise  quantity  of  water  belonging  to,  or  contained  in,  a 
substance,  is  ascertained  by  lirst  weighing  the  substance,  then  drying  it 
until  its  weight  is  constant.  The  loss  is  water. 

In  the  subjoined  table  are  given  the  average  quantities,  per  cent,  of 
water  existing  in  various  vegetable  products  when  air-dry. 

WATER  IX  AIR-DRY  PLANTS. 

Meadow  grass,  (hay,) 15 

Red  clover  hay 17 

Pine  wood 20 

Straw  and  chaff  of  wheat,  rye,  etc 15 

Bean  straw 18 

Wheat,  (rye,  oat,)  kernel 14 

Maize  kernel 12 

That  portion  of  the  water  which  the  fresh  plant  loses  by 
mere  exposure  to  the  air  is  chiefly  the  water  of  its  juices 
or  sap,  and  is  manifest  to  the  sight  and  feel  as  a  liquid,  in 
crushing  the  fresh  plant;  it  is,  properly  speaking,  thc/re^ 
water  of  vegetation.  The  water  which  remains  in  the  air- 
dry  plant  is  imperceptible  to  the  senses  while  in  the  plant, 
— can  only  be  discovered  on  expelling  it  by  heat  or  other 
wise, — and  may  be  designated  as  the  hygroscopic  water  of 
vegetation. 

The  amount  of  water  contained  in  either  fresh  or  air- 
dry  vegetable  matter  is  constantly  fluctuating  with  the 
temperature  and  the  dryness  of  the  atmosphere. 

2.    THE  CELLULOSE  GROUP,  OR  THE  AMYLOIDS. 
This  group  comprises  Cellulose,  Starch,  Imdin,  Dextrin, 
Gum,  'Cane  sugar,  Fruit  sugar,  and  Grape  sugar. 

These  bodies,  especially  cellulose  and  starch,' form  by 
far  the  larger  share — perhaps  seven-eighths — of  all  the  dry 
matter  of  vegetation,  and  most  of  them  are  distributed 
throughout  all  parts  of  plants. 

Cellulose,  C12  H00  O10. — Every  agricultural  plant  is  an 
aggregate  of  microscopic  cells,  i.  e.,  is  made  up  of  minute 
sacks  or  closed  tubes,  adhering  to  each  other. 


56 


HOW    CROPS    GROW. 


Fig.  10  represents  an  extremely  thin  slice  from  the  stem  of  a  cabbage, 
magnified  230  diameters.  The  united  walls  of  two  cells  are  seen  in  sec 
tion  at  a,  while  at  b  an  empty  space  is  noticed. 


Fig.  10. 

The  outer  coating,  or  wall,  of  the  cell  is  cellulose.  This 
substance  is  accordingly  the  skeleton  or  framework  of  the 
plant,  and  the  material  that  gives  tough 
ness  and  solidity  to  its  parts.  Next  to 
water  it  is  the  most  abundant  body  in 
the  vegetable  world. 

All  plants  and  all  parts  of  all  plants 
contain  cellulose,  but  it  is  relatively  most 
abundant  in  their  stems  and  leaves.  In 
seeds  it  forms  a  large  portion  of  the  husk, 
shell,  or  other  outer  coating,  but  in  the 
interior  of  the  seed  it  exists  in  small 
quantity. 

The  fibers  of  cotton,  (Fig.  11,  «,)  hemp, 
and  flax,  (Fig.  !!,#,)  and  white  cloth  and 
unsized  paper  made  from  these  materials, 
are  nearly  pure  cellulose. 

The  fibers  of  cotton,  hemp,  and  flax,  are  simply 
long  and    thick-walled  cells,   the    appearance   of 
which,  when  highly  magnified,  is  shown    in    fig. 
11,  where  a  represents  the  thinner,  more  soft,  and  collapsed  cotton  fiber, 
and  b  the  thicker  and  more  durable  fiber  of  linen. 


THE  VOLATILE  PART  OF  PLANTS.  57 

Wood,  or  woody  fiber,  consists  of  long  and  slender  celb 
of  various  forms  and  dimensions,  see  p.  271,)  which  are  delr- 
cate  when  young,  (in  the  sap  wood,)  but  as  they  become 
older  fill  up  interiorly  by  the  deposition  of  repeated  layers 
of  cellulose,  which  is  intergrown  with  a  substance,  (or  sub 
stances,)  called  lignin*  The  hard  shells  of  nuts  and 
stone  fruits  contain  a  basis  of  cellulose,  which  is  impreg 
nated  with  ligneous  matter. 

IWhen  quite  pure^.  cellulose  is  a  white,  often  silky  or 
spongy,  and  translucent  body,  its  appearance  varying  some 
what  according  to  the  source  whence  it  is  obtained.  In 
the  air-dry  state,  it  usually  contains  about  10°  |0  of  hygro 
scopic  water.  It  has,  in  common  with  animal  membranes, 
the  character  of  swelling  up  when  immersed  in  water,  from 
imbibing  this  liquid ;  on  drying  again,  it  shrinks  in  bulk. 
It  is  tough,  and  elastic.  » 

Cellulose  differs  remarkably  from  the  other  bodies  of 
this  group,  in  the  fact  of  its  slight  solubility  in  dilute  acids 
and  alkalies.  It  is  likewise  insoluble  in  water,  alcohol, 
ether,  the  oils,  and  in  most  ordinary  solvents.  It,  is  hence 
prepared  in  a  state  of  purity  by  acting  upon  vegetable 
matters  containing  it  with  successive  solvents,  until  all 
other  matters  are  removed. 

The  "  skeletonized "  leaves,  fruit  vessels,  etc.,  which  compose  those 
beautiful  objects  called  phantom  bouquets,  are  commonly  made  by  dis 
solving  away  the  softer  portions  of  fresh  succulent  plants  by  a  hot  solu- 

*  According  to  F.  Schulze,  lignin  impregnates,  (not  simply  incrusts,)  the 
cell-wall,  it  is  soluble  in  hot  alkaline  solutions,  and  is  readily  oxidized  by  nitric 
acid.  Schulze  ascribes  to  it  the  composition 

Carbon . .  55.3 

Hydrogen 5.8 

Oxygen 38.9 

100.0 

This  re,  however,  simply  the  inferred  composition  of  what  is  left  a'ter  the 
cellulose,  etc.,  have  been  removed.  Lignin  cannot  be  separated  in  tae  pura 
state,  and  has  never  been  analyzed.  What  is  thus  designated  is  probably  a  mix 
ture  of  several  distinct  substances. 

Lignin  appears  to  be  indigestible  by  herbivorous  animals,  (Gfrouven,  V,  Bqf- 
meuter.) 

3* 


58  HOW  CROPS   GROW. 

tion  of  caustic  soda,  and  afterwards  whitening  the  skeleton  of  fibers  that 
remains  by  means  of  chloride  of  lime,  (bleaching  powder.)  They  are  al 
most  pure  cellulose. 

Skeletons  may  also  be  prepared  by  steeping  vegetable  matters  in  a  mix 
ture  of  chlorate  of  potash,  and  dilute  nitric  acid  for  a  number  of  days. 

EXP.  22. — To  500  cubic  centimeter*,*  (or  one  pint,)  of  nitric  acid  of 
density  1.1,  add  30  grams,  (or  one  ounce,)  of  pulverized  chlorate  of  pot 
ash,  and  dissolve  the  latter  by  agitation.  Suspend  in  this  mixture  a 
number  of  leaves,  etc.,t  and  let  them  remain  undisturbed,  at  a  temper 
ature  not  above  65°  F.,  until  they  are  perfectly  whitened,  which  may  re 
quire  from  10  to  20  days.  The  preparations  of  leaves  should  be  floated 
out  from  the  solutions  on  slips  of  paper,  washed  copiously  in  clear  water, 
and  dried  under  pressure  between  folds  of  unsized  paper. 

The  fibers  of  the  whiter  and  softer  kinds  of  wood  are  now  much  em 
ployed  in  the  fabrication  of  paper.  For  this  purpose  the  wood  is  rasped 
to  a  coarse  powder  by  machinery,  then  freed  from  lignin,  starch,  etc.v 
by  a  hot  solution  of  soda,  and  finally  bleached  with  chloride  of  lime. 

The  husks  of  maize  have  been  successfully  employed  in  Austria,  both 
for  making  paper  and  an  inferior  cordage. 

Though  cellulose  is  insoluble  in,  or  but  slightly  affected 
by  dilute  acids  and  alkalies,  it  is  dissolved  or  altered  by 
these  agents,  when  they  are  concentrated  or  hot.  The 
result  of  the  action  of  strong  acids  and  alkalies  is  very 
various,  according  to  their  kind  and  the  degree  of  strength 
in  which  they  are  employed. 

The  strongest  nitric  acid  transforms  cellulose  i\\\o  nitrocellulose,  (pyrox- 
Iline,  gun  cotton,)  a  body  which  burns  explosively,  and  has  been  em 
ployed  as  a  substitute  for  gunpowder. 

Sulphuric  acid  of  a  certain  strength,  by  short  contact  with  cellulose,  con 
verts  it  a  tough,  translucent  substance  which  strongly  resembles  bladder 
or  similar  animal  membranes.  Paper,  thus  treated,  becomes  the  vegetable 
parchment  of  commerce. 

»  On  subsequent  pages  we  shall  make  frequent  use  of  some  of  the  French  dec 
imal  weights  and  measures,  for  the  reasons  that  they  are  much  more  convenient 
than  the  English  ones,  and  are  now  almost  exclusively  employed  in  all  scientific 
trestises  and  investigations.  For  small  weights,  the  gram,  abbreviated  gm., 
(equal  to  15*4  grains,  nearly),  is  the  customary  unit.  The  unit  of  measure  by  voi- 
ume  is  the  cubic  centimeter,  abbreviated  c.  c.,  (30  c.  c.  equal  one  fluid  ounce 
nearly).  Gram  weights  and  glass  measures  graduated  into  cubic  centimeters  are 
furnished  by  all  dealers  in  chemical  apparatus. 

t  Full-grown  but  not  old  leaves  of  the  elm,  maple,  and  maize,  heads  of  un 
ripe  grain,  slices  of  :he  stem  and  joints  of  maize,  etc.,  may  be  employed  to  fur 
nish  skeletons  that  will  prove  valuable  in  the  study  of  the  structure  of 
organs. 


THE  VOLATILE  FART  OF  PLANTS.  50 

EXP.  23. — To  prepare  parchment  ^oper,  fill  a  large  cylindrical  ttst  tubft 
first  to  the  depth  of  an  incli  or  so  with  water,  then  pour  in  three  times 
this  bulk  of  oil  of  vitriol,  and  mix.  When  the  liquid  is  perfectly  cool,  im 
merse  into  it  a  strip  of  unsized  paper,  aud  let  it  remain  for  about  15  sec 
onds;  then  remove,  and  rinse  it  copiously  in  water.  Lastly,  soak  for 
some  minutes  in  water,  to  which  a  little  ammonia  is  added,  and  wash 
again  with  pure  water."  These  washings  are  for  the  purpose  of  removing 
the  acid.  The  success  of  this  experiment  depends  upon  the  proper 
strength  of  the  acid,  and  the  time  of  immersion.  If  need  be,  repeat,  va 
rying  these  conditions  slightly,  until  the  result  is  obtained. 

Prolonged  contact  with  strong  sulphuric  acid  converts 
cellulose  into  dextrin,  and  finally  into  sugar,  (see  p.  75.) 
Other  intermediate  products  are,  however,  formed,  whose 
nature  is  little  understood ;  but  the  properties  of  one  of 
them  is  employed  as  a  test  for  cellulose. 

EXP.  S4.— Spread  a  slip  of  unsized  paper  upoij  a  china  plate,  and  pour 
upon  it  a  few  drops  of  the  diluted  sulphuric  acid  of  Exp.  23.  After  some 
time  the  paper  is  seen  to  swell  up  and  partly  dissolve.  Now  flow  it  with  a 
weak  solution  of  iodine,*  when  these  dissolved  portions  will  assume  n"- 
fine  and  intense  blue  color.  This  deportment  is  characteristic  of  cellulose, 
and  may  be  employed  for  its  recognition  underlie  microscope.  If  the 
experiment  be  repeated,  using  a  larger  proportion^  acid,  and  allowing 
the  action  to  continue  for  a  considerably  longer\Kie,  the  substance 
producing  the  blue  color  is  itself  destroyed  or  converted^ato  sugur,  and 
addition  of  iodine  has  no  effect.t 

Boiling  for  some  hours  with  dilute  sulphuric  acid  also 
transforms  cellulose  into  sugar,  and,  under  certain  circum 
stances,  chlorhydric  acid  and  alkalies  have  the  same 
effect  upontt: 

The  denser  and  more  impure  forms  of  cellulose,  as  they 
occur  in  wood  and  straw,  are  slowly  acted  upon  by  chemi 
cal  agents,  and  are  not  easily  digestible  by  most  animals ; 
but  the  cellulose  of  young  and  succulent  stems,  leaves,  and 
fruits,  is.  digestible  to  a  large  extent,  especially  in  the 
stomachs  of  animals  which  naturally  feed  on  herbage,  and 
therefore  cellulose  ranks  among  the  nutritive  substances,. 

•  Dissolve  a  fragment  of  iodine  as  large  as  a  wheat  kernel  in  20  c.  c.  of  alco 
hol,  add  100  c.  c.  of  vrater  to  the  solution,  aud  preserve  in  a  well  stoppered  bottle. 

t  According  to  Qrotiven,  cellulose  prepared  from  rye  straw,  (and  impure  ?) 
requires  several  hours'  action  of  sulphuric  acid  before  it  will  strike  a  blue  colot 
with  iodine,  (%er  Salznrtnder  BerlcM,  ~  467.) 


60  HOW   CROPS    GROW. 

Chemical  composition  of  cellulose. — This  body  is  a  com 
pound  of  the  three  elements,  carbon,  oxygen,  and  hydro 
gen.  Analyses  of  it,  as  prepared  from  a  multitude  of 
sources,  demonstrate  that  its  composition  is  expressed  by 
the  formula,  C13  H30  O10.  In  100  parts  it  contains 

Carbon,  44.44 
Hydrogen,  6.17 
Oxygen,  49.39 

100.00 

Modes  of  estimating  cellulose. — In  statements  of  the  composition  of 
plants,  the  terms  fiber,  woody  fiber,  and  crude  cellulose,  are  often  met  with. 
These  are  applied  to  more  or  less  impure  cellulose,  which  is  obtained  as 
a  residue  after  removing  other  matters,  as  far  as  possible,  by  alternate 
treatment  with  dilute  acids  and  alkalies,  but  without  acting  to  any  great 
extent  on  the  cellulose  itself.  The  methods  formerly  employed,  and 
those  by  which  most  of  our  analyses  have  been  made,  are  confessedly 
imperfect.  If  the  solvents  are  too  concentrated,  or  the  temperatuie  at 
which  they  act  is  too  high,  cellulose  itself  is  dissolved  ;  while  with  too 
dilute  reagents  a  portion  of  other  matters  remains  unattacked.  Tho 
method  adopted  by  Henneberg,  ( Versuchs-Stationen,  VI,  497,)  with  quite 
good  results,  is  as  follows:  3  grams  of  the  finely  divided  substance  are 
boiled  for  half  an  hour  with  200  cubic  centimeters  of  dilute  sulphuric 
acid,  (containing  1}£  per  cent  of  oil  of  vitriol,)  and  after  the  substance 
has  settled,  the  acid  liquid  is  poured  off.  The  residue  is  boiled  again 
for  half  an  hour  with  200  c.  c.  of  water,  and  this  operation  is  repeated  a 
second  time.  The  residual  substance  is  now  boiled  half  an  hour  with 
200  c.  c.  of  dilute  potash  lye,  (containing  1%  per  cent  of  dry  caustic 
potash,)  and  after  removing  the  alkaline  liquid,  it  is  boiled  twice  with 
water  as  before.  What  remains  is  brought  upon  a  filter,  and  washed 
with  water,  then  with  alcohol,  and,  lastly,  with  ether,  as  long  as  these 
solvents  take  up  anything.  This  crude  cellulose  contains  ash  and  nitro 
gen,  for  which  corrections  must  be  made.  The  nitrogen  is  assumed  to 
belong  to  some  albuminoid,  and  from  its  quantity  the  amount  of  th« 
latter  is  calculated,  (see  p.  108.) 

Even  with  these  corrections,  the  quantity  of  cellulose  is  not  obtained 
with  entire  accuracy,  as  is  usually  indicated  by  its  appearance  and  its 
composition.  While,  according  to  V.  Hofmeister,  the  crude  cellulose 
thus  prepared  from  the  pea  is  perfectly  white,  that  from  wheat  bran  ia 
brown,  and  that  from  rape-cake  is  almost  black  in  color. 

Grouven  gives  the  following  analyses  of  two  samples  of  crude  cellulost 
obtained  by  a  method  essentially  the  same  as  we  have  described.    (2to 
t,  p.  456.) 


THE  VOLATILE  PAKT  OF  PLANTS.           61 

Rye-straw  fiber.  Linen  fiber. 

Water 8.65  5.40 

Ash 2.05  1.14 

N 0.15  0.20 

C 42.47  38.36 

H 6.04  5.89 

0...                 ...40.64  48.95 


100.00  100.00 

On  deducting  water  and  ash,  and  making  proper  correction  for  the 
nitrogen,  the  above  samples,  together  with  one  of  wheat-straw  fiber, 
analyzed  by  Heuneberg,  exhibit  the  following  composition,  compared 
with  pure  cellulose. 

Rye-straw  Jiber.  Linen  fiber.  Whtat-straw  fiber.  Pare  cellulose. 

C 47.5  41.0  45.4  44.4 

H 6.8  6.4  6.3  6.2 

0 45.7  52.6  48.3  49.4 


100.0  100.0  100.0  100.0 

Franz  Schulze,  of  Rostock,  proposed  in  1857  another  method  for  esti 
mating  cellulose,  which  has  recently,  (1866,)  been  shown  to  be  more  cor 
rect  than  the  one  already  described.  Kuhn,  Aronstein,  and  H.  Schulze, 
(Henneberg^s  Journal  filr  Landwirthschaft,  1866,  pp.  289  to  297, )  have  ap 
plied  this  method  in  the  following  manner :  One  part  of  the  dry  pulver 
ized  substance,  (2  to  4  grams,)  which  has  been  previously  extracted  with 
water,  alcohol,  and  ether,  is  placed  in  a  glass-stoppered  bottle,  with  0.8 
part  of  chlorate  of  potash  and  12  parts  of  nitric  acid  of  specific  gravity 
1.10,  and  digested  at  a  temperature  not  exceeding  65°  F.  for  14  days.  At 
the  expiration  of  this  time,  the  contents  of  the  bottle  are  mixed  with 
some  water,  brought  upon  a  filter,  and  washed,  firstly,  with  cold  and 
afterwards,  with  hot  water.  When  all  the  acid  and  soluble  matters  have 
been  washed  out,  the  contents  of  the  filter  are  emptied  into  a  beaker, 
and  heated  to  165°  F.  for  about  45  minutes  with  weak  ammonia,  (1  part 
commercial  ammonia  to  50  parts  of  water) ;  the  substance  is  then  brought 
upon  a  weighed  filter,  and  washed,  first,  with  dilute  ammonia,  as  long  as 
this  passes  off  colored,  then  with  cold  and  hot  water,  then  with  alcohol, 
and,  finally,  with  ether.  The  substance  remaining  contains  a  small 
quantity  of  ash  and  nitrogen,  for  which  corrections  must  be  made.  Tha 
fiber  is,  however,  purer  than  that  procured  by  the  other  method,  and  a 
somewhat  larger  quantity,  (%  to  1%  per  cent,}  is  obtained.  The  results 
appear  to  vary  but  about  ouQper  cent  from  the  truth. 

The  average  proportions  of  cellulose  found  in  various  vegetabl* 
matters  in  the  usual  or  air-dry  state,  are  as  follows  : 


62  HOW   CROPS   GROW. 

AMOUNT  OP   CELLULOSE  IN  PLANTS. 

Per  cent.  Jfer  cent, 

Potato  tuber 1.1  Red  clover  plant  in  flower. .  .10 

Wheat  kernel 3.0          "        "       hay 34 

Wheat  ineal 0.7  Timothy        "    23 

Maize  kernel 5.5  Maize  cobs 38 

Barley      "     ... 8.0  Oat   straw 40 

Oat          "     10.3  Wheat"    48 

Buckwheat  kernel 15.0  Rye       "    54  X. 

Starch,  C13  H20  O]0.— The  cells  of  the  seeds  of  wheat, 
corn,  and  all  other  grains,  and  the  tubers  of  the  potato,  / 
contain  this  familiar  body  in  great  abundance.)  It  occupy 
also  in  the  wood  of  all  forest  trees,  especially  in  autumn 
and  winter.     It  accumulates  in  extraordinary  quantity  in 
the  pith  of  some  plants,  as  in  the  Sago-palm,  (Metroxylon 
Rumphii,)  of  the  Malay  Islands,  a  single  tree  of  which 
may  yield  800  Ibs. 

Starch  occurs  in  greater  or  less  quantity  in  every  plant 
that  has  been  examined  for  it. 

The  preparation  of  starch  from  the  potato  is  very  sim 
ple.  The  potato  contains,  on  the  average,  76  per  cent  wa 
ter,  20  per  cent  starch,  and  1  per  cent  of  cellulose,  while 
the  remaining  3  per  cent  consists  mostly  of  matters  which 
are  easily  soluble  in  water.  By  grating,  the  potatoes  are  " 
reduced  to  a  pulp ;  the  cells  are  thus  broken  and  the  starch- 
grains  set  at  liberty.  The  pulp  is  then  agitated  on  a  fine 
sieve,  in  a  stream  of  water.  The  washings  run  off  milky, 
from  suspended  starch,  while  the  cellulose  is  retained  by 
the  sieve.  The  milky  fluid  is  allowed  to  rest  in  vats  until 
the  starch  is  deposited.  It  is  then  poured  off,  and  the 
starch  is  collected  and  dried. 

Wheat-starch  is  commonly  made  by  allowing  wheaten 
flour  mixed  with  water  to  ferment  for  several  weeks.  By 
this  process  the  gluten,  etc.,  are  converted  into  soluble 
matters,  which  are  removed  by  washing,  from  the  unalter 
ed  starch. 

Starch  is  now  largely  manufactured  from  maize.     A 


THE  VOLATILE  PART  OF  PLANTS. 


,  63 


dilute  solution  of  caustic  soda  is  used  to  dissolve  the  al 
buminoids,  see  p.  95.  The  starch  and  bran  remaining,  are 
separated  by  diffusing  both  in  water,  when  the  bran  rap 
idly  settles,  and  the  water  being  run  off  at  the  proper 
time,  deposits  the  pure  starch,  corn-starch  of  commerce, 
also  known  as  maizena. 

Starcli  is  prepared  by  similar  methods  from  rice,  horse- 
chestnuts,  and  various  other  plants. 

Arrow-root  is  starch  obtained  by  grating  and  washing 
the  root-sprouts  of  Maranta  Tndtca,  and  M.  arundinacea, 
plants  native  to  the  West  Indies. 

EXP.  25.  —  Reduce  a  clean  potato  to  pulp  by  means  of  a  tin  grater. 
Tie  up  the  pulp  in  a  piece  of  not  too  fine  muslin,  and  squeeze  it  repeat 
edly  in  a  quart  or  more  of  water.  The  starch  grains  thus  pass  the 
meshes  of  the  cloth,  while  the  cellulose  is  retained.  Let  the  liquid  stand 
until  the  starch  settles,  pour  off  the  water,  and  dry  the  residue. 

Starch,  as  usually  seen,  is  a  white  powder  which  con 
sists  of  minute,  rounded  grains,  and  hence  has  a  slightly 
harsh  feel.  When  observed  under  a  powerful  magnifier, 
these  grains  often  present  characteristic  forms  and  dimen 
sions. 

In  potato-starch  they  are  egg  or  kidney-shaped,  and  are 


distinctly  marked  with  curved  lines  or  ridges,  which  sur 
round  a  point  or  eye ;  a,  fig.  12.  Wheat-starch  consists  of 
grains  shaped  like  a  thick  burning-glass,  or  spectacle-lens, 
having  a  cavity  in  the  centre,  b.  Oat-starch  is  made  up 
of  compound  grains,  which  are  easily  crushed  into  smaller 


64  _  HOW    CROPS    GROW. 

granules,  c.  In  maize  and  rice  the  grains  are  usually  so 
densely  packed  in  the  cells  as  to  present  an  angular  (six- 
sided)  outline,  as  in  d.  The  starch  of  the  bean  and  pea 
has  the  appearance  of  e.  The  minute  starch-grains  of  the 
parsnip  are  represented  at/",  and  those  of  the  beet  at  g. 

The  grains  of  potato-starch  are  among  the  largest,  be 
ing  often  1 -300th  of  an  inch  in  diameter ;  wheat-starch 
grains  are  about  1-1 000th  of  an  inch ;  those  of  rice,  l-3000th 
of  an  inch,  while  those  of  the  beet-root  are  still  smaller. 

Unorganized  Starch  exists  as  a  jelly  in  several  plants,  according  to 
Schleiden,  (Botanlk  p.  127).  Dragendorff  asserts,  that  in  the  seeds  of 
colza  and  mustard  the  starch  does  not  occur  in  the  form  of  grains,  but 
in  an  unorganized  state,  which  he  considers  to  be  the  same  as  that  no 
ticed  by  Schleiden. 

The  starch-grains  are  unacted  upon  by  cold  water,  un 
less  broken,  (see  Exp.  26,)  and  quickly  settle  from  suspen 
sion  in  it. 

When  starch  is  triturated  for  a  long  time  with  cold  water,  whereby  the 
grains  are  broken,  the  liquid,  after  filtering  or  standing  until  perfectly 
clear,  contains  starch  in  extremely  minute  quantity. 

When  starch  is  heated  to  near  boiling  with  12  to  15  times  its  weight 
of  water,  the  grains  swell  and  burst,  or  exfoliate,  the  water  is  absorbed, 
and  the  whole  forms  a  jelly.  This  is  the  starch-paste  used  by  the  laun 
dress  for  stiffening  muslin.  The  starch  is  but  very  slightly  dissolved  by 
this  treatment ;  see  Exp.  27.  On  freezing,  it  separates  almost  perfectly. 

When  starch-paste  is  dried,  it  forms  a  hard,  horn-like  mass. 

Tapioca  and  Sago  are  starch,  which,  from  being  heated  while  still 
moist,  is  partially  converted  into  starch-paste,  and,  on  drying,  acquires  a 
more  or  less  translucent  aspect.  Tapioca  is  obtained  from  the  roots  of 
the  Manihot,  a  plant  which  is  cultivated  in  the  West  Indies  and  South 
America.  Cassava  is  a  preparation  of  the  same  starch,  roasted.  Sago  is 
made  in  the  islands  of  the  East  Indian  Archipelago,  from  the  pith  of 
palms.  It  is  granulated  by  forcing  the  paste  through  metallic  sieves. 
Both  tapioca  and  sago  are  now  imitated  from  potato  starch. 

Test  for  Starch. — The  chemist  is  enabled  to  recognize 
starch  with  the  greatest  ease  and  certainty  by  its  peculiar 
deportment  towardsjiidiii^,  which,  when  dissolved  in  wa-' 
ter  or  alcohol   and  brought   in  contact  with   starch,  gives ' 
it  a  beautiful  purple  or  blue  color.     This  test  may  be  used 
even  in  microscopic  observations  with  the  utmost  facility. 


THE  VOLATILE  PART  OF  PLANTS.  65 

EXP.  26.— Shake  together  in  a  test  tube,  30  c.  c.  of  water  and  starch 
of  the  bulk  of  a  kernel  of  maize.  Add  solution  of  iodine,  drop  by  drop, 
agitating  until  a  faint  purplish  color  appears.  Pour  off  half  the  liquid 
into  another  test  tube,  and  add  at  once  to  it  one-fourth  its  bulk  of  iodine 
solution.  The  latter  portion  becomes  intensely  blue  by  transmitted,  or 
almost  black  by  reflected  light.  On  standing,  observe  that  in  the  first 
case,  where  starch  preponderates,  it  settles  to  the  bottom  leaving  a 
colorless  liquid,  which  shows  the  insolubility  of  starch  in  cold  water; 
the  starch  itself  has  a  purple  or  red  tint.  In  the  case  iodine  was  used  in 
excess,  the  deposited  starch  is  blue-black. 

EXP.  27. — Place  a  bit  of  starch  as  large  as  a  grain  of  wheat  in  30  c.  c. 
of  cold  water  and  heat  to  boiling.  The  starch  is  converted  into  thin, 
translucent  paste.  That  a  portion  is  dissolved  is  shown  by  filtering 
through  paper  and  adding  to  one-half  of  the  filtrate  a  few  drops  of  iodine 
solution,  when  a  perfectly  clear  blue  liquid  is  obtained.  The  delicacy 
of  the  reaction  is  shown  by  adding  to  30  c.  c.  of  water  a  little  solution 
of  iodine,  and  noting  that  a  few  drops  of  the  solution  of  starch  suffice  to 
make  the  large  mass  of  liquid  perceptibly  blue. 

By  the  prolonged  action  of  dry  heat,  hot  water,  acids,  / 
or  alkalies,  starch  is  converted  first  into  dextrin,  and  finally  I 
into  sugar  (glucose),  as  will  be  presently  noticed. 

The  same  transformations  are  accomplished  by  the  action 
of  living  ye  ist,  and  of  the  so-called  diastase  of  germinat 
ing  seeds ;  see  p.  328. 

The  saUva  of  man  and  plant-eating  a:iimals  usually v 
likewise  dissolves  starch  at  blood  heat  by  converting  it  in 
to  sugar.  It  is  much  more  promptly  converted  into  sugar 
by  the  liquids  of  the  large  intestine.  It  is  thus  digested 
when  eaten  by  animals.  It  i>,  in  fact,  one  of  the  most  im 
portant  ingredients  of  the  food  of  man  and  domestic  ani 
mals. 

The  action  of  saliva  demonstrates  that  starch-grains  are  not  homoge 
neous,  but  contain  a  small  proportion  of  matter  not  readily  soluble  in  this 
liquid.  This  remains  as  a  delicate  skeleton  after  the  grains  are  other 
wise  dissolved.  It  is  probably  cellulose. 

The  chemical  composition  of  starch  is  identical  witr^ 
that  of  cellulose ;  see  p.  60. 

Air-dry  starch  always  contains  a  considerable  amount 
of  hygroscopic  water,  wkich  usually  ranges  from  12  to  20 
per  cent. 


66  HOW   CROPS    GROW. 

Xext  to  water  and  cellulose,  starch  is  the  most  abundant 
ingredient  of  agricultural  plants. 

In  the  subjoined  table  are  given  the  proportions  contained  in  certain 
vegetable  products,  as  determined  by  Dr.  Dragendorff.  The  quantities 
are,  however,  somewhat  variable.  Since  the  figures  below  mostly  refer 
to  air-dry  substances,  the  proportions  of  hygroscopic  water  are  also 
Ijiven,  the  quantity  of  which  being  changeable  must  be  taken  into  ac 
count  in  making  any  strict  comparisons. 

AMOUNT  OF  STARCH  IK  PLANTS. 

Water.  Starch. 

Per  cent.  Per  cent. 

Wheat 13.2  59.5 

Wheat  flour 15.8  68.7 

Rve 11.0  59.7 

Oats 11.9  46.6 

Barley 11.5  57.5 

Timothy  seed 12.6  45.0 

Rice  (hulled) 13.3  61.7 

Peas 5.0  37.3 

Beans  (white) 16.7  33.0 

Clover  seed 10.8  10.8 

Flaxseed 7.6  23.4 

Mustard  seed 8.5  9.9 

Colza  seed 5.8  8.6 

Teitow  turnips* dry  substance  9.8 

Potatoes dry  substance  62.5 

Starch  is  quantitatively  estimated  by  various  methods. 

1.  In  case  of  potatoes  or  cereal  grains,  it  may  be  determined  rough' y 
Oy  direct  mechanical  separation.     For  this  purpose  5  to  20  grams  of  the 
substance  are  reduced  to  fine  division  by  grating  (potatoes)  or  by  soften 
ing  in  warm  water,  and  crushing  in  a  mortar  (grains).     The  pulp  thus 
obtained  is  washed  either  upon  a  fine  hair-sieve  or  in  a  bag  of  muslin, 
until  the  water  runs  off  clear.   The  starch  is  allowed  to  settle,  dried,  and 
weighed.     The  value  of  this  method  depends  upon  the  care  employed 
in  the  operations.    The  amount  of  starch  falls  out  too  low,  because  it  is 
impossible  to  break  open  all  the  minute  cells  of  the  substance  analyzed. 

2.  In  many  cases  starch  may  be  estimated  with  more  precision  by  con 
version  into  sugar;  see  p.  76. 

3.  Dr.  Drngendorff,  of  the  Rostock  Laboratory,  proceeds  with  starch  de 
terminations  as  follows :    The  pulverized  substance,   after  drying  out 
all  hygroscopic  moisture  at  212°,  is  digested  for  18  to  30  hours,  at  a  tem 
perature  of  212°,  in  10  to  12  times  its  weight  of  a  solution  of  5  to  6  parts 
of  hydrate  of  potash  in   94  to  95  parts  of  anhydrous  alcohol.     The 
digestion    must    take    place    in    sealed    glass    tubes,   or    in    a   silver 
vessel  which  admits  of  closing    perfectly.     By    this    treatment   the 

*  A  sweet  an3  mealy  turnip  grown  on  light  soils  for  table  use. 


THE  VOLATILE  PART  Or'  PLANTS.  67 

albuminoid  substances,  the  fats,  the  sugar,  and  dextrin,  are  brought 
into  such  a  condition  that  simple  washing  with  alcohol  or  water  suf 
fices  to  remove  them  completely.  The  chief  p;»rt  of  the  phosphoric 
and  silicic  acids  is  likewise  rendered  soluble.  The  starch-grains 
are  not  affected,  neither  does  tha  cellulose  undergo  alteration,  either 
qualitatively  or  quantitatively.  In  fact,  this  treatment  serves  excellently 
to  isolate  starch-grains  for  microscopic  investigations.  Besides  starch 
and  cellulose  nothing  resists  the  action  of  alcoholic  potash  save  portions 
of  cuticle,  gum,  and  some  earthy  salts. 

When  the  digestion  is  finished,  it  is  advisable,  especially  in  case  the 
substance  is  rich  in  fat,  to  bring  the  contents  of  the  tube  upon  a  filter 
while  still  hot,  as  otherwise  potash-salts  of  the  fatty  acids  may  crystallize 
out.  It  is  also  well  to  wash  immediately,  first,  with  hot  absolute  alcohol, 
then,  with  cold  alcohol  of  ordinary  strength,  and  finally,  with  cold  wa 
ter  until  these  several  solvents  remove  nothing  more.  In  the  analysis 
of  matters  which  contain  much  mucilage,  as  flaxseed,  the  washing 
must  be  completed  with  alcohol  of  8  to  10  per  cent,  to  prevent  the 
swelling  up  of  the  residue. 

The  filter  should  be  of  good  ordinary  (not  Swedish)  paper,  should  be 
washed  with  chlorhydric  acid  and  water,  dried  at  213°,  and  weighed. 
When  the  substance  is  completely  washed,  the  filter  and  its  contents 
are  dried,  first  at  130°,  and  finally  at  212°.  The  loss  consists  of  albumi 
noids,  fat,  sugar,  and  a  part  of  the  salts  of  the  substance,  and  when  the 
last  three  are  separately  estimated,  it  may  serve  to  control  the  estima 
tion,  by  elementary  analysis,  of  the  albuminoids. 

The  filter,  with  its  contents,  is  now  reduced  to  powder  or  shreds,  and 
the  whole  is  heated  with  water  containing  5  per  cent  of  chlorhydric 
acid  until  a  drop  of  the  liquid  no  longer  reacts  blue  with  iodine.  The 
treatment  with  potash  leaves  the  starch-grains  in  such  a  state  of  purity 
from  incrusting  matters,  that  their  conversion  into  dextrin  proceeds 
with  great  promptness,  and  is  accomplished  before  the  cellulose  begins 
to  be  perceptibly  acted  upon.  By  weighing  the  residue  that  remains 
from  the  action  of  chlorhydric  acid,  after  washing  and  drying,  the 
amount  of  cellulose,  cork,  lignin,  gum,  and  insoluble  fixed  matters  is 
found.  By  subtracting  these  from  the  weiu'ht  of  the  substance  after 
exhaustion  with  potash,  the  quantity  of  starch  is  learned  with  great  ac 
curacy.  The  only  error  introduced  by  this  method  lies  in  the  solution 
of  some  saline  matters  by  the  acid.  The  quantity  is,  however,  so  small 
as  rarely  to  be  appreciable.  If  needful,  it  can  be  taken  into  account  by 
evaporating  the  acid  solution  to  dryness,  incinerating  and  weighing  the 
residue  By  warming  with  concentrated  malt-extract  at  132°,  the  starch 
ulone  is  taken  into  solution,  and  no  correction  is  needed  for  saline  mat 
ters.  If  it  is  wished  to  determine  the  su»-ar  produced  by  the  transfor 
mation  of  the  starch,  a  weaker  acid  must  of  course  be  employed.  In  case 
of  mucilaginous  substances,  the  starch  must  be  extracted  by  digestion 
with  a  strong  solution  of  chloride  of  sodium,  with  which  the  requisite 
quantity  of  chlorhyuric  acid  has  been  mixed,  and  the  residue  should  b« 


68  HOW   CROPS    GROW. 

washed  with  water  to  which  some  alcohol  has  been  added.-  -ffnmeberft 
Jownal  fiir  Landmrthschaft,  1862,  p.  206. 

Inulill,  Cia  IT20  O10,  closely  resembles  starch  in  many 
points,  and  appears  to  replace  that  body  in  the  roots  of 
the  artichoke,  elecampane,  dahlia,  dandelion,  chicory,  and 
other  plants  of  the  same  natural  family  (compositce).  It 
may  be  obtained  in  the  form  of  minute  white  grains, 
which  dissolve  easily  in  hot  water,  and  mostly  separate 
again  as  the  water  cools,  (Unlike  starch,  inulin  exists  in  a 
liquid  form  in  the  roots  above  named,  and  separates  in 
grains  from  the  clear  pressed  juice  when  this  is  kept  some 
time.  According  to  Bouchardat,  the  juice  of  the  dahlia 
tuber,  expressed  in  winter,  becomes  a  semi-solid  white  mass 
in  this  way,  after  reposing  some  hours,  from  the  separa- 
cion  of  8  per  cent  of  this  substance. 

Inulin,  when  pure,  gives  no  coloration  with  iodine.  It 
may  be  recognized  in  plants,  where  it  occurs  in  a  solution 
usually  of  the  consistence  of  a  thin  oil,  by  soaking  a  slice 
of  the  plant  in  strong  alcohol.  Inulin  is  insoluble  in  this 
liquid,  and  under  its  influence  shortly  separates  as  a  solid 
in  the  form  of  spherical  granules,  which  may  be  identified 
with -the  aid  of  the  microscope. 

When  long  boiled  with  water  it  is  slowly  but  complete 
ly  converted  into  a  kind  of  sugar,  (levulose)  ;  hot  dilute 
acids  accomplish  the  same  transformation  In  a  short  time. 
It  is  digested  by  animals,  and  doubtless  has  the  same  value 
for  food  as  starch. 

In  chemical  composition,  inulin  agrees  perfectly  with 
cellulose  and  starch  ;  see  p.  60. 

Dextrin,  Cia  H20  O10,  has  been  thought  to  occur  in  small  \ 
quantity  dissolved  in  the  sap  of  all  plants.     According  to  ' 
Von  Bibra's  late  investigations,  the  substance  existing  in 
bread-grains  which  earlier  experimenters  believed  to  be 
dextrin,  is  in  reality  gum.     Busse,  who  has  still  more 
recently  examined  various  young  cereal  plants  and  seeds, 


THE  VOLATILE  PART  OF  PLANTS.  69 

and  potato  tubers,  for  dextrin,  found  it  only  in  oj^jjiotatoes 
and  young  wheat  plants,  and  there  in  very  small  quantity. 
— Jahresbericht  fur  Chemie,  1866,  p.  664. 

Dextrin  is  easily  prepared  artificially  by  the  transforma-  \ 
tion  of  starch,  and  its  interest  to  us  is  chiefly  due  to  this 
fact.     When  starch  is  exposed  some  hours  to  the  heat  of 
an  oven,  or  30  minutes  to  the  temperature  of  415°  F.,  the 
grains  swell,  burst  open,  and  are  gradually  converted  into 
a  light-brown  substance,  which  dissolves  readily  in  water, 
forming  a  clear,  gummy  solution.     This  is  dextrin,  and  thus    I 
prepared  it  is  largely  used  in  the  arts,  especially  in  calico- 
printing,  as  a  cheap  substitute  for  gum  arabic,  and  bears    1 
the  name  British  gum.     In  the  baking  of  bread  it  is  form 
ed  from  the  starch  of  the  flour,  and  often  constitutes  ten 
per  cent  of  the  loaf.     The  glazing  on  the  crust  of  bread, 
or  upon  biscuits  that  have  been  steamed,  is  chiefly  due  to 
a  coating  of  dextrin.  (  Dextrin  is  thus  an  important  ingre-  ^ 
dient  of  those  kinds  of  food  which  are  prepared  from  the   / 
starchy  grains  by  cooking. 

British  gum,  or  commercial  dextrin,  appears  either  in 
translucent  brown  masses,  or  as  a  yellowish- white  powder. 
On  addition  of  cold  water,  the  dextrin  readily  dissolves, 
leaving  behind  a  portion  of  unaltered  starch.  When  the 
solution  is  mixed  with  strong  alcohol,  the  dextrin  separates 
in  wliito  flocks,  which,  upon  agitation,  unite  to  translucent 
salvy  clumps.  With  iodine,  solution  of  commercial  dex 
trin  gives  a  fine  purplish-red  color.  Pure  dextrin  is,  how-  \ ' 
ever,  unaffected  by  iodine. 

EXP.  28. — Cautiously  heat  a  spoonful  of  powdered  starch  in  a  porce 
lain  dish,  with  constant  stirring  so  that  it  may  not  burn,  for  the  space 
of  five  minutes ;  it  acquires  a  yellow,  and  later,  a  brown  color.  Now 
add  thrice  its  bulk  of  water,  and  heat  nearly  to  boiling.  Observe  that  a 
slimy  solution  is  formed.  Pour  it  upon  a  tilter ;  the  liquid  that  runs 
through  contains  dextrin.  To  a  portion,  add  twice  its  bulk  of  alcohol ; 
dextrin  is  precipitated.  To  another  portion,  add  solution  of  iodine;  thid 
shows  the  presence  of  dissolved  but  unaltered  starch,  which  likewise  re 
mains  solid  in  considerable  quantities  upon  the  niter.  To  a  third  portion 


70  HOW    CROPS   GROW. 

of  the  filtrate  add  one  drop  of  strong  sulphuric  acid,  and  boil  a  few 
minutes.  Test  with  iodine,  which  will  now  prove  that  all  the  starch  is 
transformed. 

Not  only  heat,  but  likewise  acids  and  ferments  produce 
dextrin  from  starch,  and  also  from  cellulose.  In  the 
sprouting  of  seeds  it  is  formed  from  starch,  and  hence  i» 
an  ingredient  of  malt  liquors.  It  is  often  contained  in 
the  animal  body.  Limpricht  obtained  nearly  a  pound  of 
dextrin  from  200  Ibs.  of  the  flesh  of  a  young  horse. — Ann. 
Ch.  Ph.,  133,  p.  295. 

The  chemical  composition  of  dextrin  is  the  same  as  that 
of  cellulose,  starch,  and  inulin. 

The  Gums. — A  number  of  bodies  exist  in  the  vegetable 
kingdom,  which,  from  the  similarity  of  their  properties, 
have  received  the  common  designation  of  Gums.  The 

O 

best  known  are  Gum  Arabic,  or  Arabin  •  the  gum  of  the 
Cherry  and  Plum,  or  Cerasin  ;  Gum  Tragacanth  and  Bas- 
sora  Gum,  or  Bassorin ;  and  the  Vegetable  Mucilage  of 
various  roots,  viz.,  of  mallow  and  oomfrey ;  and  of  certain 
seeds,  as  those  of  flax  and  quince, 

Arabin. — Gum  Arabic  or  Arabin  exudes  from  the 
stems  of  various  species  of  acacia  that  grow  in  the  tropi 
cal  countries  of  the  East,  especially  in  Arabia  and  Egypt. 
It  occurs  in  tear-like,  transparent,  and,  in  its  purest  form, 
colorless  masses.  These  dissolve  easily  in  their  own  weight 
of  water,  forming  a  viscid  liquid,  or  mucilage,  which  is  em 
ployed  for  causing  adhesion  between  surfaces  of  paper, 
arid  for  thickening  colors  in  calico-printing.  Gum  Arabic, 
when  burned,  leaves  about  3"  per  cent  of  ash,  chiefly  car 
bonates  of  lime  and  potash  ;  it  is,  in  fact,  a  compound  of 
lime  and  potash  with  Arabic  acid. 

Arabic  A<*i«l  is  obtained  pure  by  mixing  a  strong  solution  of  guni 
Arabic  with  clilorhydric  acid,  and  adding  alcohol.  It  is  thus  pre 
cipitated  as  a  milk-white  mass,  which,  when  dried  at  212",  becomes 
trau .-parent,  and  has  the  composition  C]2  Haa  O,,. 


THE   VOLATILE    PART    OF   PLANTS. 


71 


In  100  parts,  Arabic  acid  contains  : 

Carbon  42.12 
Hydrogen  6.41 
Oxygen  51.47 

100.00 

By  exposure  to  a  temperature  of  250°,  Arabic  acid  loses  one  molecule 
of  water,  and  becomes  insoluble  in  water,  being  transformed  into 
Metarabic  Acid,  (Fremy's  Acide  metagummique). 

Ccrasin.  —  The  gum  which  frequently  forms  glassy 
masses  on  the  bark  of  cherry,  plum,  apricot,  peach,  and 
almond  trees,  is  a  mixture  in  variable  proportions  of 
Arabin,  or  the  arabates  of  lime  and  potash,  with  cerasin, 
or  the  metarabates  of  lime  and  potash.  Cold  water  dis 
solves  the  former,  while  the  cerasin  remains  undissolved, 
but  swollen  to  a  pasty  mass  or  jelly. 

]JIetaral>ic  Acid,  is  prepared,  as  above  stated,  by  exposing  Arabic 
acid  to  a  temperature  of  250°  F.,  and  its  composition  is  C12  H20  O10.  It 
is  likewise  produced  by  putting  solution  of  gum  Arabic  in  contact  with 
oil  of  vitriol.  On  the  other  hand,  metarabic  acid  is  converted  into  Arabic 
acid,  by  boiling  with  water  and  a  little  lime  or  alkali.  Metarabic  acid, 
as  well  as  its  compounds  with  lime,  potash,  etc.,  are  insoluble  in  water. 

Bassorin,  C12  H20  O10,  as  found  in  Gum  Tragacanth,  has 
much  similarity  to  metarabic  acid  in  its  properties,  being 
insoluble  in  water,  but  swelling  up  in  it  to  a  paste  or  jelly. 

Vegetable  Mucilage,  C12  H20  O19,   n 

has  the  same  composition,  and  near-    a  \ 
ly  the  same  characters  as  Bassorin, 
and  is  possibly  identical  with  it.   It 

i  pLlrtuniversal  constituent 

It  is  procured  in  a  state  of  purity  by  soak- 
ing  unbroken  flaxseed  in  cold  water,  with 
frequent  agitation,  heating  the  liquid  to 
boiling,  straining,  and  evaporating,  until 
addition  of  alcohol  separates  tenacious 
threads  from  it.  It  is  then  precipitated  by 
alcohol  containing  a  little  chlorhydric 

acid,  and  washed  by  the  same  mixture.     On  drying,  it  forms  a  homy, 
colorless,  and  friable  mass.    Fig.  13  represents  a  highly  magnified  see 


72  HOW   CROPS   GROW. 

tion  of  the  flaxseed.   The  external  cells,  a,  contain  the  mucilage.    Whet 
soaked  in  water,  the  mucilage  swells,  bursts  the  cells,  and  exudes. 

One  or  other  of  these  kinds  of  gum  has  been  found  in 
the  following  plants,  viz.,  basswood,  elm,  apple,  grape, 
castor-oil  bean,  mangold,  tea,  sunflower,  pepper,  in  various 
sea-weeds,  and  in  the  seeds  of  wheat,  rye,  barley,  oats, 
maize,  rice,  buckwheat,  and  millet. 

In  the  bread-grains,  Arabin,  or  at  least  a  soluble  gum, 
occurs  often  in  considerable  proportion. 

TABLE    OF    THE     PROPORTIONS    (per  cent)   OP   GUM    IN    VARIOUS   AIR-DBI 
PLANTS  OR  PARTS  OF  PLANTS. 

(According  to  VonBibra,  Die  Getreidearten  und  das  Brod.) 

Wheat  kernel 4.50 

Wheat  flour,  superfine 6.25 

Spelt  flour,  (Triticum  spelta,) 2.48 

Wheat  bran 8.85 

Spelt  bran 12.52 

Rye  kernel 4.10 

Rye  flour 7.25 

Rye  bnm 10.40 

Barley  flour 6.33 

Barley  bran • 6.88 

Oat  meal 3.50 

Rice  flour 2.00 

Millet  flour 10.60 

Maize  meal 3.05 

Buckwheat  flour 2.85 

The  gums  are  converted  into  sugar  by  long  boiling  with 
dilute  acids. 

The  recent  experiments  of  Grouven  show  that,  contrary 
,  to  what  has  been  taught  hitherto,  gum,  (at  least  gum 
Arabic,)  is  digestible  by  domestic  animals. 

Saccharose  or  Cane  Sugar,  C19  H2Q  On,  so  called  be 
cause  first  and  chiefly  prepared  from  the 
eugar  cane,  is  the  ordinary  sugar  of  com 
merce.     When  pure,  it  is  a  white  solid, 
readily  soluble  in  water,  forming  a  color-  Fig-  14- 

kss,  ropy,  and  intensely  sweet  solution.     It  crystallizes  in 
rhombic  prisms,  fig.   14,  which  are  usually  small,  as  in 


THE  VOLATILE  PART  OF  PLANTS.          75 

granulated  sugar,  but  in  the  form  of  rock  candy  may  be 
found  an  inch  or  more  in  length.  The  crystallized  sugar 
obtained  largely  from  the  sugar-beet,  in  Europe,  and  that 
furnished  in  the  United  States  by  the  sugar-maple  and 
sorghum,  when  pure,  are  identical  with  cane-sugar. 

Saccharose  also  exists  in  the  vernal  juices  of  the  walnut, 
birch,  and  other  trees.  It  occurs  in  the  stems  of  unripe 
maize,  in  the  nectar  of  flowers,  in  fresh  honey,  in  parsnips, 
turnips,  carrots,  parsley,  sweet  potatoes,  in  the  stems  and 
roots  of  grasses,  and  in  a  multitude  of  fruits. 

EXP.  29. — Heat  cautiously  a  spoonful  of  white  sugar  until  it  melts,  (at 
356°  F.,)  to  a  clear  yellow  liquid.  On  rapid  cooling,  it  gives  a  transpar 
ent  mass,  known  as  barley  sugar,  which  is  employed  in  confectionery. 
At  a  higher  heat,  it  turns  brown,  froths,  emits  pungent  vapors,  and  be 
comes  burnt  sugar,  or  caramel,  which  is  used  for  coloring  soups,  ale,  etc 

The  quantity  per  cent  of  saccharose  in  the  juice  of  various  plants  is 
given  in  the  annexed  table.  It  is,  of  course,  variable,  depending  upon 
the  variety  of  plant  in  case,  of  cane,  beet,  and  sorghum,  as  well  as  upon 
the  stage  of  growth. 

SACCHAROSE  IN  PLANTS. 

per  cent. 

Sugar  cane,  average 18      Peligot 

Sugar  beet,        "       10  " 

Sorghum 9%  Goessmann 

Maize,  just  flowered, 3%  Ludersdorff 

Sugar  maple,  sap,average 2j^  Liebig 

Red  maple,       "        "        2%      " 

"When  a  solution  of  this  sugar  is  heated  with  dilute    J 
acids,  or  when  acted  oi\  by  yeast,  it  is  converted  into  a  mix-   / 
ture  of  equal  parts  of  levulose,  (fruit  sugar,)  and  glucose,  f 
(grape  sugar.) 

The  composition  of  saccharose  is  the  same  as  that  of 
Arabic  acid,  and  it  contains  in  100  parts : 
Carbon      42.11 
Hydrogen    6.43 
Oxygen      51.46 

100.00 

Levulose,  or  Fruit  Sugar,  (Fructose,)  Cia  H34  O12,  exists 
mixed  with  other  sugars  in  sweet  fruits,  honey,  and  mo- 
4 


74  now  CROPS  GROW. 

lasses.  Timlin  is  converted  into  this  sugai  by  long  boil 
ing  with  dilute  acids,  \r  with  water  alone.  When  pure, 
it  is  a  colorless,  amorphous*  mass.  It  is  incapable  of  crys 
tallizing  or  granulating,  and  usually  exists  dissolved  in  a 
small  proportion  of  water  as  a  syrup.  Its  sweetness  is 
equal  to  that  of  saccharose. 

^vulose  contains  in  100  parts : 

Carbon       40.00 

Hydrogen    6.67 

Oxygen      53.33 

100.00 

Glucose  or  Grape  Sugar,  C12  H24  O12,  naturally  occurs 
associated  with  levulose  in  the  juices  of  plants  and  in 
honey.  Granules  of  glucose  separate  from  the  juice  of  the 
grape  in  drying,  as  may  be  seen  in  old  "  candied  "  raisins. 
Honey  often  granulates,  or  candies,  on  long  keeping,  from 
th£  crystallization  of  a  part  of  its  glucose. 
(Glucose  is  formed  from  dextrin  by  the  action  of  hot 
dilute  :u-'uU,  imiK1  same  way  (lint  levulose  is  produced 
from  inulnT  In  th&jmre  state  it  exists  as  minute,  color 
less  crystalsJ^aH^^tsJweight  for  weight,  but  half  as  sweet  - 
as  the  foregoing  sugars.  In  composition  it  is  identical 
with  levulose. 

It  combines  chemically  with  water  in  two  proportions.  Mono-hy- 
drated  glucose,  (Cia  H34  Oia  HaO,)  or  Anthon's  hard  crystallized  grape- 
sugar,  which  is  prepared  in  Germany  by  a  secret  process,  is  dry  to  the 
feel.  Bi-hydrated  glucose,  (C13  H24  Oi3  2H2O,)  occurs  in  commerce  in  an 
impure  state  as  a  soft,  sticky,  crystalline  mass,  which  becomes  doughy 
at  a  slightly  elevated  temperature.  Both  these  hydrates  lose  their  crystai- 
wrater  at  212°. 

Dissolved  in  water,  glucose  yields  a  syrup,  which  is 
thin,  and  destitute  of  the  ropiness  of  cane-sugar  syrup. 
It  does  not  crystallize,  (granulate,)  so  readily  as  cane-sugar. 

Exi».  30. — Mix  100  c.  c.  of  water  with  30  drops  of  strong  sulphuric 
acid,  and  heat  to  vigorous  boiling  in  a  glass  flask.  Stir  10  grams  of 

*  laterally  without  shape,  i.  e.,  not  crystallized. 


THE  VOLATILE  PART  OF  PLANTS.  75 

•tarch  with  a  little  water,  and  pour  the  mixture  into  the  hd  liquid,  drop 
by  drop,  so  as  not  to  interrupt  the  boiling.  The  starch  dissolves,  and 
passes  first  into  dextrin,  and  finally  into  glucose.  Continue  the  ebul 
lition  for  several  hours,  replacing  the  evaporated  water  from  time  to 
time.  To  remove  the  sulphuric  acid,  add  to  the  liquid,  which  may  be 
Btill  milky  from  impurities  in  the  starch,  powdered  chalk,  until  the  sour 
taste  disappears ;  filter  from  the  sulphate  of  lime,  (gypsum,)  that  ie 
formed,  and  evaporate  the  solution  of  glucose*  at  a  gentle  heat  to  a 
syrupy  consistence.  On  long  standing  it  may  crystallize  or  granulate. 

By  this  method  is  prepared  the  so-called  potato-sugar,  or  starch-sugar 
of  commerce,  which  is  added  to  grape-juice  for  making  a  stronger  wine, 
and  is  also  employed  to  adulterate  cane  or  beet-sugar. 

In  the  sprouting  and  malting  of  grain,  glucosef  is  like 
wise  produced  fromjstarch. 

Even  cellulose  is  convertible  into  glucose  by  the  pro 
longed  actrntTof  hot  dilute  acids,  and  saw-dust  has  thus 
been  made  to  yield  an  impure  syrup,  suitable  for  the  pro 
duction  of  alcohol. 

In  the  formation  of  glucose  from  cellulose,  starch,  and  dextrin,  the 
latter  substances  take  up  the  elements  of  water  as  represented  by  the 
equation 

Starch,  &c.  Wate*.  Glucose. 

C12H20O10     +     2H20    —    C12H24O12 

In  this  process,  90  parts  of  starch,  &c.,  yield  100  parts  of  glucose. 

Trommels  Copper  test. — A  characteristic  test  for  glucose  and  levulose 
is  found  in  their  deportment  towards  an  alkaline  solution  of  oxide  of 
copper,  which  readily  yields  up  oxygen  to  these  sugars,  being  itself  re 
duced  to  yellow  or  red  suboxide. 

EXP.  31. — Prepare  the  copper  test  by  dissolving  together  in  30  c.  c.  of 
warm  water  a  pinch  of  sulphate  of  copper  and  one  of  tartaric  acid ;  add 
to  the  liquid,  solution  of  caustic  potash  until  it  feels  slippery  to  the 
skin.  Place  in  separate  test  tubes  a  few  drops  of  solution  of  cane-sugar, 
a  similar  amount  of  the  dextrin  solution,  obtained  in  Exp.  38;  of  solu 
tion  of  glucose,  from  raisins,  or  from  Exp.  30;  and  of  molasses;  add  to 
each  a  little  of  the  copper  solution,  and  place  them  in  a  vessel  of  hot 

*  If  the  boiling  has  been  kept  up  but  an  hour  or  so,  the  glucose  will  contain 
dextrin,  as  may  be  ascertained  by  mixing  a  small  portion  of  the  still  acid  liquid 
with  5  times  its  bulk  of  strong  alcohol,  which  will  precipitate  dextrin,  but  not 
glucose. 

t  According  to  some  authorities,  the  sugar  of  malt  is  distinct  from' glucose, 
and  has  been  designated  maltose.  Probably,  however,  the  so-called  maltose  is  a 
mixture  of  glucose  and  dextrin. 


76  HOW   CROPS   GROW. 

water.  Observe  that  the  saccharose  and  dextrin  suffer  no  alteration  for 
a  long  time,  while  the  glucose  and  molasses  shortly  cause  the  separation 
of  suboxide  of  copper. 

EXP.  32.—  Heat  to  boiling  a  little  white  cane-sugar  with  30  e.  c.  of 
water,  and  3  drops  of  strong  sulphuric  acid,  in  a  glass  or  porcelain  dish, 
for  15  minutes,  supplying  the  waste  of  water  as  needful,  and  test  the 
liquid  as  in  the  last  Exp.  It  will  be  found  that  this  treatment  trans- 
forms  saccharose  into  glucose,  (and  levulose.) 

Tfie  quaittit  itive  estimation  of  the  sugars  and  of  starch  is  commonly 
based  upon  the  reaction  just  described.  For  this  purpose  the  alkaline 
copper  solution  is  made  of  a  known  strength  by  dissolving  a  given  weight 
of  sulphate  of  copper,  etc.,  in  a  given  volume  of  water,  and  the  glucose, 
or  levulose,  or  a  mixture  of  both,  being  likewise  made  to  a  known  vol 
ume  of  solution,  it  is  allowed  to  flow  slowly  from  a  graduated  tube  into 
a  measured  portion  of  warm  copper  solution,  until  the  blue  color  is  dis 
charged.  Experiment  has  demonstrated  that  one  part  of  glucose  or 
of  levulose  reduces  2.205  +  parts  of  oxide  of  copper.  Starch  and  sac 
charose  are  first  converted  into  glucose  and  levulose,  by  heating  with  an 
acid,  and  then  examined  in  the  same  manner.  For  the  details  required 
/  to  ensure  accuracy,  consult  Fresenius'  (Juant&ttive  Analysis. 

As  already  stated,  cane-sugar,  by  long  boiling  of  its 
/     aqueous  solution,  and  under  the  influence  of  hot  dilute 
acids  (Exp.  32)  and  yeast,  loses  its  property  of  ready  crys- 
V      tallization,  and  is  converted  into  levulose  and  glucose. 

According  to  Dubrunfaut,  two  molecules  of  cane-sugar  take  up  the 
elements  of  two  molecules,  (5.26  per  cent,)  of  water,  yielding  a  mixture 
of  equal  parts  of  levulose  and  glucose.  This  change  is  expressed  In 
chemical  symbols  as  follows : 

2  (Cia  H22  ()„)  +  2  H2O  =  C,a  H24  O13  +  C12  H24  Oia 
Cane-sugar.         Water.          Levulone.  Gliicose. 

The  alterability  of  saccharose  on  heating  its  solutions 
occasions  a  loss  of  one-third  to  one-half  of  what  is  really 
contained  in  cane-juice,  and  is  one  reason  that  solid  sugar 
is  obtained  from  the  sorghum  with  such  difficulty.  Mo 
lasses,  sorghum  syrup,  and  honey,  usually  contain  all  three 
of  these  sugars.  In  molasses,  both  the  saccharose  and 
glucose  are  hindered  from  crystallization  by  the  levulose, 
and  by  saline  matters  derived  from  the  cane-juice. 

Honey-dew,  that  sometimes  falls  in  viscid  drops  from 
the  leaves  of  the  lime  and  other  trees,  is  essentially  a  mix- 


THE  VOLATILE  PABT  OP  PLANTS*  ?7 


tare  of  tlie  three  sugars  with  some  gum.    'The  mannas  of 
Syria  and  Kurdistan  are  of  similar  composition*' 

The  older  observers  assumed  the  presence  of  glucose  in 
the  bread  grains.  Thus  Vauquelin  found,  or  thought  he 
found,  8.5°|c  of  this  sugar  in  Odessa  wheat.  More  recent-"* 
ly,  Peligot,  Mitscherlich,  and  Stein  have  denied  the  pres 
ence  of  any  sugar  in  these  grains.  In  his  work  on  the 
Cereals  and  Bread,  (Die  G-etreidearten  und  das  Brod, 
I860,)  p.  163,  Von  Bibra  has  reinvestigated  this  question, 
and  found  in  fresh  ground  wheat,  etc.,  a  sugar  having 
some  of  the  characters  of  saccharose,  and  others^  of  glucose 
and  levulose.  It  is,  therefore,  a  mixture. 

Von  Bibra  found  in  the  flour  of  various  grains  the  following  quan 
tities  of  sugar. 

PROPORTIONS  OF  SUGAR  IN  AIR-DSY  FLOUR,  BRAN,  AND  MEAL. 

Per  cent. 

Wheat  flour 2.33 

Spelt  flour 1.41 

Wheat  bran 4.30 

Spelt  bran 2.70 

Rye  flour 3.46 

Rye  bran 1. 86 

Barley  meal 3.04 

Barley  bran    1.90 

Oat  mea .    ., 2.19 

Rice  flour  0.39 

Millet  flour 1.30 

Maize  meal 3.71 

Buckwheat  meal 0.91 

Qlucosides. — There  occur  in  the  vegetable  kingdom  a 
large  number  of  bodies,  usually  bitter  in  taste,  which  con 
tain  glucose,  or  a  similar  sugar,  chemically  combined 
with  other  substances,  or  yield  it  on  decomposition. 
Tannin^  the  bitter  principle  of  oak  and  hemlock  ba'rk ; 
salicm,  from  willow  bark ;  phloridzin,  from  the  bark  of 
the  apple-tree  root,  and  principles  contained  in  jalap, 
scammony,  the  horse  chestnut,  and  almond,  are  of  this 
kind.  The  sugar  may  be  obtained  from  these  so-called 
.glucosides  by  heating  with  dilute  acids. 


78  HOW    CEOPS    GHOW. 

Other  st. gars. — Other  sugars  or  saccharoid  bodies  occurring  in  common 
or  cultivated  plants,  but  requiring  iro  extended  notice  here,  are  the  fo* 
lowing: — 

Mannite,  C8  H,4  Oa,  is  abundant  in  the  so-called  manna  of  the  apothe- 
caiy,  which  exudes  from  the  bark  of  several  species  of  ash  that  grow  in 
tho  Eastern  Hemisphere,  (Fraxvuus  ormis  and  rotundifolia.)  It  like 
wise  exists  in  the  sap  of  our  fruit  trees,  in  edible  mushrooms,  and  some 
times  is  formed  in  the  fermentation  of  sugar,  (viscous  fermentation.) 
It  appears  in  minute  colorless  crystals,  and  has  a  sweetish  taste. 

Quercite,  C9  Hi2  O5,  is  the  sweet  principle  of  the  acorn,  from  which  it 
may  be  procured  in  colorless  crystals. 

finite,  C«  Hj2  O6,  exudes  from  wounds  in  the  bark  of  a  Californian  and 
Australian  pine,  (Pinus  Lambertiana.)  Separated  from  the  resin  that 
usually  accompanies  it,  it  forms  a  white  crystalline  mass  of  a  very  sweet 
taste. 

Mycose,  Cia  H22  On,  is  a  sugar  found  in  ergot  of  rye.  It  may  be  ob 
tained  in  crystals,  and  is  very  sweet. 

Sugar  of  Milk,  Lactose,  d2  H22  On  +  H2O,  is  the  sweet  principle  of  the 
milk  of  animals.  It  is  largely  prepared  for  commerce,  in  Switzerland, 
by  evaporating  whey,  (milk  from  which  casein  and  fat  have  been  sepa 
rated  for  making  cheese.)  In  a  state  of  purity,  it  forms  transparent,  col 
orless  crystals,  which  crackle  under  the  teeth,  and  are  but  slightly  sweet 
to  the  taste.  When  dissolved  to  saturation  in  water,  it  forms  a  sweet 
but  thin  syrup. 

Mutual  transformation*  of  the  members  of  the  Cellulose 
Group. — One  of  the  most  remarkable  facts  in  the  history 
of  this  group  of  bodies  is  the  facility  with  which  its  mem 
bers  undergo  mutual  conversion.  Some  of  these  changes 
have  been  already  noticed,  but  we  may  appropriately  re 
view  them  here. 

a.  Transformations  in  the  plant. — The  machinery  of  the 
vegetable  organism  has  the  power  to  transform  most,  if 
not  all,  of  these  bodies  into  every  other  one,  and  we  find 
nearly  all  of  them  in  every  individual  of  the  higher  order 
of  plants  in  some  one  or  other  stage  of  its  growth. 

In  germmation,  the  starch  which  is  largely  contained  in 
seeds  is  converted  into  dextrin  and  glucose.  It  thereby 
acquires  solubility,  and  passes  into  the  embryo  to  feed  the 
young  plant.  Here  it  is  again  solidified  as  cellulose,  starch, 
or  other  organic  principle,  yielding,  in  fact,  the  chief  part 
of  the  materials  for  the  structure  of  the  seedling. 


THE    VOLATILE    PAxtT    OF  PLANTS. 

At  spring-time,  in  cold  climates,  the  starch  stored  up 
over  winter  in  the  new  wood  of  many  trees,  especially  the 
maple,  appears  to  be  converted  into  the  saccharose  which 
is  found  so  abundantly  in  the  sap,  and  this  sugar,  carried 
upwards  to  the  buds,  nourishes  the  young  leaves,  and  is 
there  transformed  into  cellulose,  and  into  starch  again. 

The  sugar-beet  root,  when  healthy,  yields  a  juice  con 
taining  10  to  14  per  cent  of  saccharose,  and  is  destitute  of 
starch.  Schacht  has  observed  that  in  a  certain  diseased 
state  of  the  beet,  its  sugar  is  partially  converted  into  starch, 
grains  of  this  substance  making  their  appearance.  (  Wll- 
dtfs  Gentralblatt,  1863,  II.,  p.  217.) 

The  analysis  of  the  cereal  grains  sometimes  reveals  the 
presence  of  dextrin,  at  others  of  sugar  or  gum. 

Thus  Stepf  found  no  dextrin,  but  both  gum  arid  sugar  in  maize-meal, 
(Jour,  fur  Prakt.  Chem.,  76,  p.  92;)  while  Fresenitis,  in  a  more  recent 
analysis,  (Vs.  St.,  1,  p.  180,)  obtained  dextrin,  but  neither  sugar  or  gum. 
The  sample  of  maize  examined  by  Stepf  contained  3.05  p.  c.  gum  and 
3.71  p.  c.  sugar;  that  analyzed  by  Fresenius  yielded  2.33  p.  c.  dextrin. 

Gum  Tragacanth  is  a  result  of  the  transformation  of 
cellulose,  as  Mohl  has  shown  by  its  microscopic  study. 

b.  In  the  animal,  the  substances  we  have  been  describ 
ing  also  suffer  transformation  when  employed  as  food. ! 
During  the  process  of  digestion,  cellulose,  so  far  as  it  is 
acted  upon,  starch,  dextrin,  and  probably  the  gums,  are  j 
all  converted  into  glucose. 

c.'  Many  of  these  changes  may  also  be  produced  apart 
from  physiological  agency,  by  the  action  of  heat,  acids,  and     / 
ferments,  operating  singly  or  jointly. 

Cellulose  and  starch  are  converted  by  boiling  with  M 
dilute  acid,  into  dextrin  and  finally  into  glucose.  IT  paper 
or  cotton  be  placed  in  contact  with  strong  chlorhydric 
acid,  (spirit  of  salt,)  it  is  gradually  converted  into  the 
same  sugar.  Cellulose  ar  d  starch  acted  upon  for  some 
time  by  strong  nitric  acid,  (aqua-fortis,)  give  compounds 
from  which  dextrin  may  be  separated.  Nitrocellulose, 
(gun  cotton,)  sometimes  yields  gum  by  its  spontaneous 


HOW   CROPS    GROW. 

decomposition,  (Hoffmann,  Quart.  Jour.  dhem.  Soc.,  jx 
767.)  A  kind  of  gum  also  appears  in  solutions  of  cane- 
sugar  or  in  beet-juice,  when  they  ferment  under  certain 
conditions.  Inulin  and  the  gums  yield  sugar,  (levulose,) 
but  no  dextrin,  when  boiled  with  weak  acids. 

d.  It  will  be  noticed  that  while  physical  and  chemical 
agencies  produce  these  metamorphoses  in  one  direction,  it 
is  only  under  the  influence  of  life  that  they  can  be  accom 
plished  in  the  reverse  manner. 

In  the  laboratory  we  can  only  reduce  from  a  ^higher, 
organized,  or  more  complex  constitution  to  a  lower  and 
simpler  one.  In  the  vegetable,  however,  all  these  changes, 
and  many  more,  take  place  with  the  greatest  facility.  (  ^ . 

The  Chemical  Composition  of  the  Uellufose  Group. — 
It  is  a  remarkable  fact  that  all  the  substances  just  de 
scribed  stand  very  closely  related  to  each  other  in  chemical 
composition,  while  several  of  them  are  identical  in  this 
respect.  In  the  following  table  their  composition  is  ex 
pressed  in  formula. 

CHEMICAL  FORMULAE  OF  THE  BODIES  OP  THE  CELLULOSE  GROUP. 


Cellulose 
Starch 
Inulir 
Dextnii 
Bassorin 
Veg.  Mucilago 
Metarabic  acid 
Arabic  acid 


C13HaoOig 


Ara1  lc13HaaOn 

Cane  sugar 

Fruit  sugar  I  n    TT    r* 

Grape  sugar  [C»H>«°'« 

It  will  be  observed  that  all  these  bodies  contain  12 
atoms  of  carbon,  united  to  as  much  hydrogen  and  oxygen 
as  form  10,  11,  or  12  molecules  of  water.  We  can,  there 
fore,  conceive  of  their  conversion  one  into  another,  with 
no  further  change  in  chemical  composition  in  any 
than  the  loss  or  gain  of  a  few  molecules  of  water. 


V 


THE  VOLATILE  PART  OF  PLANTS.  81 


Ismnerism. — Bodies  which — like  cellulose  and  dextrin,  or  .ike  levulose 
and  glucose— are  identical  in  composition,  and  yet  are  characterize^,  by 
different  properties  and  modes  of  occurrence,  are  termed  isotnertc;  they 
are  examples  of  isomerism.  These  words  are  of  Greek  derivation,  and 
signify  of  equal  measure. 

We  must  suppose  that  the  particles  of  isomeric  bodies  which  are  com 
posed  of  the  same  kinds  of  matter  and  in  the  same  quantities,  exist  in 
different  states  of  arrangement.  The  mason  can  build  from  a  given  num 
ber  of  bricks  and  a  certain  amount  of  mortar,  a  simple  wall,  an  aqueduct, 
a  bridge  or  a  castle.  The  composition  of  these  unlike  structures  may 
be  the  same,  both  in  kind  and  quantity ;  but  the  structures  themselves 
differ  immensely,  from  the  fact  of  the  diverse  arrangement  of  their  ma 
terials.  In  the  same  manner  we  may  suppose  starch  to  be  converted 
into  dextrin  by  a  change  in  the  relative  positions  of  the  atoms  of  carbon, 
hydrogen,  and  oxygen,  which  compose  them. 

3,  THE  PECTOSE  GKOUP. — The  pectose  group  includes 
Pectose,  Pectin,  Pectosic,  Pectic,  and  Metapectic  acids. 
These  bodies  exist  in,  or  are  derived  from,  fleshy  fruits^ 
including  pumpkins  and  squashes,  berries,  the  roots  of 
the  turnip,  beet,  onion,  and  carrot,  and  in  cabbage  and 
celery.  They  are  an  important  part  of  the  food  of  men 
and  cattle. 

PectOSC  is  the  name  given  to  a  body  which  is  supposed     , 
rather  than  demonstrated  to  occur  with  cellulose  in  the 
flesh  of  unripe  fruits,  and  in  the  roots  of  turnips,  carrots,    / 
and  beets.     Its  characters  in  the  pure  state  are  as  good  as   < 
unknown,  because  we  are  as  yet  acquainted  with  no  means 
of  separating  it  from  cellulose  without  changing  its  nature. 
Pectose  is  thought  to  constitute  the  chief  bulk  of  the  dry 
matter  of  the  above-mentioned  fruits  and  roots,  and  is  con 
cluded  to  be  a  distinct  body  by  the  products  of  its  trans 
formation,  either  such  as  are  formed  naturally,  or  those 
procured  b;  artificial  means.     In  what  follows,  we  shall  as 
sume,  with  Fremy,  (Ann.  de  Chim.  et  de  Phys.,  XXIV, 
6,)  that  pectose  exists,  and  is  the  source  of  pectin,  etc. 

Pectin  is  produced  from  pectose  in  a  manner  similar  to 

that  by  which  dextrin  is  obtained  from  cellulose  or  starch, 

viz.,  by  the  action  of  heat,  of  acids,  and  of  ferments.,  When 

the  flesh  of  fruits,  or  the  roots  whic^  consist  chiefly  of 

4,* 


82  HOW   CROPS   GROW. 

pectose,  are  subjected  to  the  joint  action  of  a  moderate  ; 
heat  and  an  acid,  the  starch  they  contain  is  slowly  altered  I 
into  dextrin  and  sugar,  while  the  firm  pectose  shortly  soft-  ' 
ens,  becomes  soluble  in  water,  and  is  converted  into  pec-  ; 
tin.     It  is  precisely  these  changes  which  occur  in  the  bak 
ing  of  apples  and  pears,  and  in  the  boiling  of  turnips,  car 
rots,  etc.,  with  water.     In  the  ripening  of  fruits  the  same   ; 
transformation  takes  place.     The  firm  pectose,  under  the   j 
influence  of  the  acids  that  exist  in  all  fruits,  gradaally  soft-  j 
ens,  and  passes  into  pectin. 

EXP.  33. — Express,  and,  if  turbid,  filter  through  muslin  the  juice  of  a 
ripe  apple,  pear,  or  peach.  Add  to  the  clear  liquid  its  own  bulk  of  al 
cohol.  Pectin  is  precipitated  as  a  stringy,  gelatinous  mass,  which,  on 
drying,  shrinks  greatly  in  bulk,  and  forms,  if  pure,  a  white  substance 
that  may  be  easily  reduced  to  powder,  and  is  readLy  soluble  in  cold 
•water. 

EXP.  34. — Reduce  several  white  turnips  or  beets  to  pulp  by  grating. 
Inclose  the  pulp  in  a  piece  of  muslin,  and  wash  by  squeezing  in  water 
until  all  soluble  matters  are  removed,  or  until  the  water  comes  off  nearly 
tasteless.  Bring  the  washed  pulp  into  a  glass  vessel,  with  enough  dilute 
chlorhydric  acid,  (1  part  by  bulk  of  commercial  muriatic  acid  to  15 
parts  of  water,)  to  saturate  the  mass,  and  let  it  stand  48  hours.  Squeeze 
out  the  acid  liquid,  filter  it,  and  add  alcohol,  when  pectin  will  separate. 

The  strong  aqueous  solution  of  pectin  is  viscid  or  gummy, 
as  seen  in  the  juice  that  exudes  from  baked  apples  or  pears. 

PectOSic  and  Pectic  acids. — Under  the  action  of  a  fer- 
I  ment  occurring  in  many  fruits,  assisted  by  a  gentle  heat, 
J  pectin  is  transformed  first  into  pectosic,  and  afterward  into 
!i  pectic  acid.     These  bodies  compose  the  well-known  fruit- 
jellies.    They  are  both  insoluble  in  cold  water,  and  remain 
.    suspended  in  it  as  a  gelatinous  mass.     Pectosic  acid  is 
soluble  in  boiling  water,  and  hence  most  fruit  jellies  bo- 
come  liquid  when  heated  to  boiling;  on  cooling,  its  solu 
tion  gelatinizes  again.     Pectic  acid  is  insoluble  even  in 
foiling  water.     It  is  formed  also  when  the  pulp  of  fruits 
or  roots  containing  pectose  is  acted  on  by  alkalies  or  by 
ammonia-oxide  of  copper.     The  latter  agent,  (a  solvent 
of  cellulose,)  converts  pectose  directly  into  pectic  acid, 


THE    VOLATILE    PART    OF    PLANTS.  88 

which    remains  in   insoluble  combination  with  oxide  of 
copper. 

Uletapectic  acid.1 — By  too  long  boiling,  by  prolonged  contact 
with  acids  or  alkalies,  and  by  decay,  the  pectic  and  pectosic  acids,  as  well 
as  pectin,  are  transformed  into  still  another  substance,  viz.,  metapectic 
ancl,  which,  according  to  Fremy,  is  a  very  soluble  body  of  quite  sour 
tasle.  It  is  the  last  product  of  the  transformation  of  the  bodies  of  this 
group  with  which  we  are  acquainted.  It  exists,  according  to  Fremy,  in 
beet-molasses  and  decayed  fruits. 

EXP.  35. — Stew  a  handful  of  sound  cranberries,  covered  with  water- 
just  long  enough  to  make  them  soft.  Observe  the  speedy  solution  of 
the  firm  pectose.  Strain  through  muslin.  The  juice  contains  soluble 
pectin,  which  may  be  precipitated  from  a  small  portion  by  alcohol. 
Keep  the  remaining  juice  heated  to  near  the  boiling  point  in  a  water 
bath,  (i.  e.,  by  immersing  the  vessel  containing  it  in  a  larger  one  of  boil 
ing  water.)  After  a  time,  which  is  variable  according  to  the  condition  of 
the  fruit,  and  must  be  ascertained  by  trial,  the  juice  on  cooling  or  stand 
ing  solidifies  to  a  jelly,  that  dissolves  on  warming,  and  reappears  again 
on  cooling — Fremy's  pectosic  acid.  By  further  heating,  the  juice  may 
form  a  jelly  which  is  permanent  when  hot — pectic  acid — and  on  still 
longer  exposure  to  the  same  temperature,  this  jelly  may  dissolve  again, 
by  passing  into  Fremy's  metapectic  acid,  which  alcohol  does  not  precip 
itate. 

Other  ripe  fruits,  as  quinces,  strawberries,  peaches,  grapes,  apples,  etc., 
may  be  employed  for  this  experiment,  but  in  any  case  the  time  required 
for  the  juice  to  run  through  these  changes  cannot  be  predicted  safely, 
and  the  student  may  easily  fail  in  attempting  to  follow  them. 

Chemical  compos  it  ion,  of  the  Pectose  group. — Our  knowl 
edge  on  this  point  is  very  imperfect.     Pectose  itself,  hav 
ing  never  been  obtained  pure,  has  not  been  analysed.  The 
other  bodies  of  this  group  have  been  examined,  but,  owing 
to  the  difficulty  of  obtaining  them  in  a  state  of  purity,  the 
results  of  different  observers  are  discordant. 
The  formulae  of  FEEMT  are  as  follows : 
Pectose,  unknown. 

Pectin,  C32  H40  O28     +     4  R2  O 

Pectosic  acid,       C18  H20  O14     +     1^  H2  O 
Pectic  acid,          C18  H20  O14     +     II2  O 
Metapectic  acid,  C8  H10  O7      +    2  H2  O 

Grouven,  (2ter  Salzmunder  Bericht,  p.  470,)  has  prepar 
ed  pectin  on  the  large  scale  from  beet-root  cake,  (remaining 
after  the  juice  was  expressed  for  smgar  manufacture,)  h~ 


84  HOW   CKOPS   GROW. 

digesting  it.  with  cold  dilute  chlorhydric  acid,  precipitat 
ing  and  washing  with  alcohol.  Thus  obtained,  it  had  all 
the  characters  ascribed  to  pectin.  Its  centesimal  com 
position,  however,  corresponded  nearly  with  that  assigned 
by  Fremy  to  pecti  acid,  and  differs  somewhat  from  that 
given  by  this  cheu  ist  for  pectin,  as  is  seen  from  the  suf 
joined  figures : 

Pectin.  Pecticacid.  Grouven's  pectin. 

C  M  H48  08a  Cie  H«  016 

Carbon 40.67  43.29                     42.95 

Hydrogen 5.08  4.84                      5.44 

Oxygen 54.25  52.87                     51.61 

100.00  100.00  •    100.00 

From  the  best  analyses  and  from  analogy  with  cellulose 
it  is  probable  that  pectose  has  the  same  composition  as 
pectin,  or  differs  from  it  only  by  a  few  molecules  of  water. 
If  we  subtract  the  water,  which  in  the  formulae  (p.  83)  is 
separated  by  +  from  the  remaining  symbol,  we  see  that 
the  proportions  of  Carbon,  Hydrogen,  and  Oxygen  are  the 
same  in  all  these  bodies,  and  correspond  to  the  formula 
C8  H10  O,.  This  nearness  of  composition  assists  in  com 
prehending  the  ease  with  which  the  transformations  of 
pectose  into  the  other  members  of  the  group  are  effected. 

Relations  of  the  Cellulose  and  Pectose  Groups. — It  was 
formerly  thought  that  the  pectinbodies  are  convertible 
into  sugar  by  the  prolonged  action  of  acids.  Fremy  has 
showntBat  this  is  not  the  case. 

Sacc,  (Ann.  Gh.  et  Phys.,  25,  218,)  and  Porter,  (Ann. 
Ch.  et  Pharm.,  71,  115,)  have  investigated  a  body  having 
the  properties  and  nearly  the  composition  of  pectic  acid, 
which  is  produced  by  the  action  of  nitric  acid  on  wood. 

Divers,  (Jour.  Vliem.  Soc.,  1863,  p.  91,)  has  observed 
«  mxostance  having  the  essential  characters  of  pectic  acid 
among  the  productw  of  the  spontaneous  decomposition  of 
nitrocellulose,  (gun  cotton.) 

It  is  probable,  though   not   yet  fairly  demonstrated, 


THE  VOLATILE  PART   OF   PLANTS.  85 

that  in  the  living  plant  cellulose  passes  into  pectose  and 

;ctin.     Without  loubt,  also,  the  reverse  transformations 
iay  be  readily  accomplished. 

4.  THE  VEGETABLE  ACIDS. — The  Vegetable  Acids  are 
very  numerous.  (  Some  of  them  are  found  in  all  classes  of 
plants,  and  nearly  every  family  of  the  vegetable  kingdom 
contains  one  or  several  acids  peculiar  to  itself,  j  Those 
which  concern  us  here  are  few  in  number,  and  though 
doubtless  of  the  highest  importance  in  the  economy  of 
vegetation,  are  of  subordinate  interest  to  the  objects  of 
this  work,  and  will  be  noticed  but  briefly.  They  are 
oxalic,  tartaric,  malic,  and  citric  acids.  They  occur  in 
plants  either  in  the  free  state,  or  as  salts  of  lime,  potash, 
etc.  I  They  are  mostly  found  in  fruits.  \ 

Oxalic  acid,  C2  H2  O4  2  Ha  O,  exists  largely  in  the  com- 
mon  sorrel,  and,  according  to  the  best 
observers,   is  found   in   greater   or   less 
quantity  in  nearly  all  plants.     The  pure 
acid  presents  itself  in  the  form  of  color 
less,  brilliant,  transparent    crystals,  not 
unlike  Epsom  salts  in  appearance,  (Fig. 
15,)  but  having  an  intensely  sour  taste. 
(Oxalic  acid  forms  with  lime  a  salt-^-ihe  oxalate  of  lime 
— which  is  insoluble  in  pure  water.     It  nevertheless  exists 
dissolved  in  the  sells  of  plants,  so  long  as  they  are  in  active 
growth,  (Schmidt,  Ann.  Chem.  u.  Pharm.,  61,297.)     To 
wards  the  end  of  the  period  of  growth,  it  often  accumu 
lates  in  such  quantity  as  to  separate  in  microscopic  crystals. 
These  are  found  in  large  quantity  in  the  mature  leaves  and    1 
roots  of  the  beet,  in  the  root  of  garden  rhubarb,  and  espe-  / 
cially  in  many  lichens. 

Oxalate  of  potash  is  soluble  in  water,  and  exists  in  the 
juices  of  sorrel  and  garden  rhubarb.  It  was  formerly 
used  for  removing  ink-stains  from  cloth  and  leather,  under 
whe  name  of  salt  of  sorrel.  Oxalic  acid  is  now  employed 
for  this  purpose.  Oxalate  of  soda  is  soluble  in  water,  and 


86  HOW    UKOPS   GROW. 

is  found  in  the  juices  of  plants  that  grow  on  the  sea-shore* 
Oxalate  of  ammonia  is  employed  as  a  test  for  lime. 

EXP.  36. — Dissolve  5  giims  of  oxalic  acid  in  50  c.  c.  of  hot  water,  add 
solution  of  ammonia  or  solid  carbonate  of  ammonia  until  the  odor  of  the 
latter  slightly  prevails,  and  allow  the  liquid  to  cool  slowly.  Long,  needle 
like  crystals  of  a  salt  of  oxalic  acid  and  ammonia — the  oxalate  of  ammonia 
— separate  on  cooling,  the  compound  being  sparingly  soluble  in  coid  wa 
ter.  Preserve  for  future  use. 

EXP.  37. — Add  to  any  solution  of  lime,  as  lime-water,  (see  note,  p.  36,) 
or  hard  well  water,  a  few  drops  of  oxalate  of  ammonia  solution.  Oxalate 
of  lime  immediately  appears  as  a  white  powdery  precipitate,  which,  from 
its  extreme  insolubility,  serves  to  indicate  tbe  presence  of  the  minutest 
quantities  of  lime.  Add  a  few  drops  of  chlorhydric  or  nitric  acid  to  the 
oxalate  of  lime ;  it  disappears.  Hence  oxalate  of  ammonia  is  a  test  fo 
lime  only  in  solutions  containing  no  free  mineral  acid.  (Acetic  ana 
oxalic  acids,  however,  have  little  effect  upon  the  test.) 

Definition  of  Acids,  JBases,  and  Salts. — In  the  popular  \ 
sense,  an  acid  is  any  body  having  a  sour  taste.     It  is,  in  j 
fact,  true  that  all  sour  substances  are  acids,  but  all  acids 
are  not  sour,  some  being  tasteless,  others  bitter,  and  some 
sweet.  ;  A  better  characteristic  of  an  acid  is  its  capability  j 
of  combining  chemically  with  bases.     The  strongest  acids, 
i.  e.  those  bodies  whose  acid  characters  are  most  strongly 
developed,  if  soluble,  so  as  to  have  any  effect  on  the  nerves 
of  taste,   are  sour,  viz.,  sulphuric  acid,  phosphoric  acid, 
nitric  acid,  etc. 

liases  are  the  opposite  of  acids.  The  strongest  bases, 
when  soluble,  are  bitter  and  biting  to  the  taste,  and  cor 
rode  the  skin.  Potash,  soda,  ammonia,  and  lime,  are  ex 
amples.  Magnesia,  oxide  of  iron,  and  many  other  com 
pounds  of  metals  with  oxygen,  are  insoluble  bases,  and 
hence  destitute  of  taste.  Potash,  soda,  and  ammonia,  are 
termed  alkalies  •  lime  and  magnesia,  alkali-earths. 

Salts  are  compounds  of  acids  and  bases,  or  at  least  re 
sult  from  their  chemical  union.  Thus,  in  Exp.  20,  the  salt, 
phosphate  of  lime,  was  produced  by  bringing  together 
phosphoric  acid,  and  the  base,  lime.  In  Exp.  37,  oxalato 
of  lime  was  made  in  a  similar  manner.  Common  salt — in 


THE   VOLATILE    PART    OF    PLANTS.  87 

chemical  language,  chloride  of  sodium — is  formed  when 
soda  is  mixed  with  chlorhydric  acid,  water  being,  in  this 
case,  produced  at  the  same  time. 

Test  for  acidx  and  alkalies. — Many  vegetable  colors  are  altered  by  solu 
ble  acids  or  soluble  bases,  (alkalies,)  in  such  a  manner  as  to  answer  the 
purpose  of  distinguishing  these  two  classes  of  bodies.    A  solution  of 
cochineal  may  be  employed.    It  has  a  ruby-red  color  when  concentrat 
ed,  but  on  mixing  with  much  pure  water,  becomes  orange  or  yellowish-  \ 
orange.   Acids  do  not  affect  this  color,  while  alkalies  turn  it  to  an  intense   / 
carmine  or  violet-carmine,  which  is  restored  to  orange  by  acids.  / 

EXP.  38.— Prepare  tincture  *  of  cochineal  by  pulverizing  3  grams  of 
cochineal,  and  shaking  frequently  with  a  mixture  of  50  c.  c.  of  strong 
alcohol  and  200  c.  c.  of  water.  After  a  day  or  two,  pour  off  the  clear 
liquid  for  use. 

To  a  cup  of  water  add  a  few  drops  of  strong  sulphuric  acid,  and  to  an 
other  similar  quantity  add  as  many  drops  of  ammonia.  To  the  liquids 
add  separately  5  drops  of  cochineal  tincture,  observing  the  coloration  in 
each  case.  D.vide  the  dilute  ammonia  into  two  portions,  and  pour  into 
one  of  them  the  dilute  acid,  until  the  carmine  color  just  passes  into 
orange.  Should  excess  of  acid  have  been  incautiously  used,  add  ammo 
nia,  until  the  carmine  reappears,  and  destroy  it  again  by  new  portions 
of  acid,  added  dropwise.  The  acid  and  base,  thus  neutralize  each  other,  and 
the  solution  contains  sulphate  of  ammonia,  but  no  free  acid  or  base.  It 
will  be  found  that  the  orange-cochineal  indicates  very  minute  quantities 
of  ammonia,  and  the  carmine-cochineal  correspondingly  small  quantities 
of  acid.  Tincture  of  litmus,  (procurable  of  the  apothecary,)  or  of  dried 
red  cabbage,  may  also  be  employed.  Litmus  is  made  red  by  soluble 
acids,  and  blue  by  soluble  bases.  With  red  cabbage,  acids  develope  a 
purple,  and  the  bases  a  green  color. 

In  the  formation  of  salts,  the  acids  and  bases  more  or  less  neutralize 
sach  otfier's  properties,  and  their  compounds,  when  soluble,  have  a  less 
sour  or  less  acrid  taste,  and  act  less  vigorously  on  vegetable  colors  than 
the  acids  or  bases  themselves.  Some  soluble  salts  have  no  taste  at  all 
resembling  either  their  base  or  acid,  and  have  no  effect  on  vegetable  col 
ors.  This  is  true  of  common  salt,  glauber  salts  or  sulphate  of  soda,  and 
saltpeter  or  nitrate  of  potash.  Others  exhibit  the  properties  of  their 
base,  though  in  a  reduced  degree.  Carbonate  of  ammonia,  for  example, 
has  much  of  the  odor,  taste,  and  effect  on  vegetable  colors  that  belong 
to  ammonia.  Carbonate  of  soda  has  the  taste  and  other  properties  of 
caustic  soda  in  a  greatly  mitigated  form.  On  the  other  hand,  sulphates  of 
alumina,  iron,  and  copper,  have  slightly  acid  characters. 

Certain  acids  form  with  the  same  base  several  distinct  salts.  Thus 
carbonic  acid  and  soda  may  produce  carbonate  of  soda,  Na-jO  COa,  01 


•  Tinctures,  in  the  language  of  the  apothecary,  are  alcoholic  solution*. 


88  HOW   CROPS   GROW. 

bicarb&aate  of  soda,  Na  H  0  CO2.  The  latter  is  mu  th  less  alkaline  than 
the  former,  but  both  turn  cochineal  to  a  carmine  color.  Again,  phos 
phoric  acid  may  form  three  distinct  salts  with  soda  or  with  lime,  which 
will  be  noticed  in  another  place.  Oxalic  acid  also  yields  several  kinds 
of  salts,  us  do  the  other  organic  acids  presently  to  be  described. 

Malic  acid,  C4  H6  O6,  is  the  chief  sour  principle  of  ap 
ples,  currants,  gooseberries,  plums,  cherries,  strawberries^ 
and  most  common  fruits.  It  exists  in  small  quantity  in  a 
multitude  of  plants.  It  is  found  abundantly  in  combina 
tion  with  potash,  in  the  garden  rhubarb,  and  malate  of 
potash  may  be  obtained  in  crystals  by  simply  evaporating 
the  juice  of  the  leaf-stalks  of  this  plant.  It  is  likewise 
abundant  as  lime-salt  in  the  nearly  ripe  berries  of  the 
mountain  ash,  and  in  barberries.  Malate  of  lime  also 
occurs  in  considerable  quantity  in  the  leaves  of  tobacco, 
and  is  often  encountered  in  the  manufacture  of  maple  su 
gar,  separating  as  a  white  or  gray  sandy  powder  during 
the  evaporation  of  the  sap. 

Pure  malic  acid  is  only  seen  in  the  chemical  laboratory, 
and  presents  white,  crystalline  masses  of  an  intensely  sour 
taste.  It  is  extremely  soluble  in  water. 

Tartaric  acid,  C4  II,  O6,  is  abundant  in  the  grape,  from 
the  juice  of  which,  during  fermentation,  it  is  deposited  in 
combination  with  potash  as  argol.  This, 
on  purification,  yields  the  cream  of  tartar, 
(bitartrate  of  potash, )  of  commerce.  Tar- 
trates  of  potash  or  lime  exist  in  small 
quantities  in  tamarinds,  in  the  unripe  ber-  Fig.  16. 

ries  of  the  mountain  ash,  in  the  berries  of  the  sumach,  in 
cucumbers,  potatoes,  pine-apples,  and  many  other  fruits. 
The  acid  itself  may  be  obtained  in  large  glassy  crystals, 
(see  Fig.  16,)  which  are  very  sour  to  the  taste. 

Citric  acid,  C6  H8  O7,  exists  in  the  free  state  in  the  juicb 
of  the  lemon,  and  in  unripe  tomatoes.  It  accompaniea 
malic  acid  in  the  currant,  gooseberry,  cherry,  strawberry, 
and  raspberry. )  It  is  found  in  small  quantity,  united  to 


THE  VOLATILE  PART  OF  PLANTS.  89 

lime,  ni  tobacco  leaves,  in  the  tubers  of  the  Jerusalem 
artichoke,  in  the  bulbs  of  onions,  in  beet  roots,  in  coffee- 
berries,  and  in  the  needles  of  the  fir  tree. 

In  the  pure  state,  citric  acid  forms  large  transparent  j 
or  white  crystals,  very  sour  to  the  taste. 

Relations  of  the  Vegetable  Acids  to  each  other  and  to  the  Amyloids. — The 
four  acids  above  noticed  usually  occur  together  in  our  ordinary  fruita 
and  it  appears  that  some  of  them  undergo  mutual  conversion  in  the  liv 
ing  plant. 

According  to  Liebig,  the  unripe  berries  of  the  mountain  ash  contain 
much  tartaric  acid,  which,  as  the  fruit  ripens,  is  converted  into  malic 
acid.    Schmidt,  (Ann.  Chem.  u.  Pharm.,  114,  109,)  first  showed  that  tar 
taric  acid  can  be  artificially  transformed  into  malic  acid.    Tire  chemical 
change  consists  merely  in  the  removal  of  one  atom  of  oxygen, 
Tartaric  acid.         Malic  acid. 
C4  Hfl  O9  —  O  —  C4  H6  06 

When  citric,  malic,  and  tartaric  acids  are  boiled  with  nitric  acid,  or 
heated  with  caustic  potash,  they  all  yield  oxalic  acid. 

Cellulose,  starch,  dextrin,  the  sugars,  and,  according  to  some,  pectic 
acid,  yield  oxalic  acid,  when  heated  with  potash  or  nitric  acid.  Com 
mercial  oxalic  acid  is  thu,s  made  from  starch  and  from  saw-dust. 

Gum  (Arabic,)  sugar,  starch,  and,  according  to  some,  pectin,  yield  tar 
taric  acid  by  the  action  of  nitric  acid. 

5*  FATS  AND  OILS  (WAX). — We  have  only  space  here 
to  notice  this  important  class  of  bodies  in  a  very  general 
manner,  (jhi  all  plants  and  nearly  all  parts  of  plantsj 
we  find  some  representatives  of  this  group ;  but  it  is 
chiefly  in  certain  seeds  that  they  occur  most  abundantly. 
Tims  the  seeds  of  hemp,  flax,  colzn,  cotton,  bayberry, 
pea-nut,  butternut,  beech,  hickory,  almond,  sunflower, 
etc.,  contain  10  to  70  per  cent  of  oil,  which  may  be  in 
great  part  removed  by  pressure.  In  some  plants,  as  the 
common  bayberry,  and  the  tallow-tree  of  Nicaragua,  the 
fat  is  solid  at  ordinary  temperatures,  and  must  be  extracted 
by  aid  of  heat ;  while,  in  most  cases,  the  fatty  matter  is 
liquid.  /The  cereal  grams,  especially  oats  and  maize,  con 
tain  oil  in  appreciable  quantity.  The  mode  of  occurrence 
of  oil  in  plants  is  shown  in  fig.  17,  which  represents  a 
highly  magnified  section  of  the  flax-seed.  The  oil  exists 


90 


HOW   CHOPS    GROW. 


as  minute,  transparent  globules  in  the  cells,  f.  From 
these  seeds  the  oil  may  be  completely  extracted  by  ether, 
benzine,  or  sulphide  of  carbon, 
which  dissolve  all  fats  with  readi 
ness,  but  scarcely  affect  the  other 
vegetable  principles. 

Many  plants  yield  small  quan 
tities  of  wax,  which  either  gives  a 
glossy  coat  to  their  leaves,  or 
forms  a  bloom  upon  their  fruit. 
The  lower  leaves  of  the  oat  plant 
at  the  time  of  blossom  contain,  in 
the  dry  state,  10  per  cent  of  fat 
and  wax,  (Arendt) .  Scarcely  two 
of  these  oils,  fats,  or  kinds  of  wax,  are  exactly  alike  in 
their  propertit-s.  They  differ  more  or  less  in  taste,  odor, 
and  consistency,  as  well  as  in  their  chemical  composition. 

EXP.  39 — Place  a  handful  of  fine  and  fresh  corn  or  oat  meal  which  has 
been  dried  for  an  hour  or  so  at  a  heat  not  exceeding  212°,  in  a  bottle. 
Pour  on  twice  its  bulk  of  ether,  cork  tightly,  and  agitate  frequently  for 
half  an  hour.  Drain  off  the  liquid  (filter,  if  need  be)  into  a  clean  porce 
lain  dish,  and  allow  the  ether  to  evaporate.  A  yellowish  oil  remains, 
which,  by  gently  warming  for  some  time,  loses  the  smell  of  ether  and 
becomes  quite  pure. 

The  fatty  oils  must  not  be  confounded  with  the  ethereal^ 
essential,  or  volatile  oik.     The  former  do  not  evaporate 
except  at  a  high  temperature,  and  when  brought  upon 
paper  leave  a  permanent  u  grease-spot."    The  latter  readily  v< 
volatilize,  leaving  no  trace  of  their  presence.     The  forme r,  • 
when  pure,  are  without  smell  or  taste.     The  latter  usually  | 
possess  marked  odorspfrkioh  adttpfmany  of  them  to  use 
as  perfumes. 

In  the  animal  body,  fat  (in  some  insects,  wax,)  is  formed 
or  appropriated  from  the  food,  and  accumulates  in  consid* 
erable  quantities.  How  to  feed  an  animal  so  as  to  cause 
the  most  rapid  and  economical  fattening  is  one  of  the 
most  important  questions  of  agricultural  chemistry. 


THE    VOLATILE    PART    OF    PL^  NTS.  91 

However  greatly  the  various  fats  may  differ  in  external 
o  iracters,  they  are  all  mixtures  of  a  few  elementary  fats. 
The  most  abundant  and  commonly  occurring  fats,  espe 
cially  those  which  are  ingredients  of  the  food  of  man  and 
domestic  animals,  viz. :  tallow,  olive  oil,  and  butter,  con 
sist  essentially  of  three  substances,  which  we  may  briefly 
notice.  These  elementary  fats  are  Stearin,  Palmitin,  and 
Olein*  and  they  consist  of  carbon,  oxygen,  and  hydrogen, 
the  first-named  element  being  greatly  preponderant. 


Stearin  is  represented  by  the  formula  C57  Hno  O8. 
is  the  most  abundant  ingredient  of  the  common  fats,  and 
exists  in  largest  proportion  in  the  harder  kinds  of  tallow. 


it\ 
IM 


EXP.  40. — Heat  mutton  or  beef  tallow,  in  a  bottle  that  may  be  tightly 
corked,  with  tpc  times  its  bulk  of  concentrated  ether,  until  a  clear  solu 
tion  is  obtain  ju.  Let  cool  slowly,  when  stearin  will  crystallize  out  in 
pearly  scales. 

Palnntill,  C61  H98  OB,  receives  its  name  from  the  palm 
oil,  of  Africa,  in  which  it  is  a  large  ingredient.  It 
forms  a  good  part  of  butter,  and  is  one  of  the  chief  con 
stituents  of  bees-wax,  and  of  bayberry  tallow. 

Olein,  C67  H104  O6,  is  the  liquid  ingredient  of  fats,  and 
occurs  most  abundantly  in  the  oils.  It  is  prepared  from 
olive  oil  by  cooling  down  to  the  freezing  point,  when  the 
stearin  and  palmitin  solidify,  leaving  the  olein  still  in  the 
liquid  state. 

Other  elementary  fats,  viz. :  butyrin,  laurin,  myristin,  etc.,  occur  in 
small  quantity  in  butter,  and  in  various  vegetable  oils.  Fluxseed  oil 
certains  liuolein;  castor  oil,  ricinolein,  etc. 

We  have  already  given  the  formulae  of  the  principal 
Pats,  but  for  our  purposes,  a  better  idea  of  their  composi 
tion  may  be  gathered  from  a  centesimal  statement,  viz. ; 


*  Margarin,  formerly  thought  to  he  a  distinct  fat,  is  a  mixture  of  stearin  and 
jMtlmitln. 


92  HOW   CROPS   GROW. 

CENTESIMAL    COMPOSITION    OF   THE    ELEMENTARY   FATS. 

Stearin.  Palmitin.  Olein. 

Carbon,               76.6              75.9  77.4 

Hydrogen,           12.4              12.2  11.8 

Oxygen,               10.0               11.9  10.8 


100.0  100.0  100.0 

Phosphorized  fats. — The  animal  brain  and  spinal  cord, 
and  the  yolk  of  the  egg,  contain  a  considerable  amount  of 
fat  which  has  long  been  characterized  by  a  small  con 
tent  of  phosphorus.  Yon  Bibra  found  the  quantity  of 
phosphorus  in  this  (impure)  fat  to  range  from  1.21  to  2.53 
per  cent.  Knop  (  Vs.  St.  1,  p.  26)  was  the  first  to  show  that 
analogous  phosphorized  fats  exist  in  plants.  From  the 
sugar  pea  he  extracted  2.5  per  cent  of  a  thick  brown  oil, 
which  was  free  from  sulphur  and  nitrogen,  but  contained 
1.25  per  cent  of  phosphorus. 

The  composition  of  this  oil  was  as  follows : 

Carbon 66.85 

Hydrogen 9.53 

Oxygen 22.38 

Phosphorus 1.25 

100.00 

Topler  (Henneber^s  Jahresbericht  1859—1860,  p.  164) 
subsequently  examined  the  oils  of  a  large  number  of  seeds 
for  phosphorus  with  the  subjoined  results : 


Source  of  Per  cent  of 

fat.  phosphorus. 

Lupine 0.29 

Pea   1.17 

Horse  bean 0.72 

Vetch 0.50 

Winter  lentil 0.39 

Horse-chestnut 0.30 

Chocolate  bean none 

Millet " 

Poppy " 


Source  of  Jfcr  cent  of 

fat.  phosphorus 

Walnut trace 

Olive none 

Wheat 0.25 

Barley 0.28 

Rye 0.31 

Oat 0.44 

Flax non* 

Colza " 

Mustard " 


THE   VOLATIIE    PART   OP   PLANT'S.  93 

According  to  Hoppe-Seyler,  (Med.  Chem.  Unters.,  I,)  the  phosphorized 
principle  of  oil  of  maize,  and  of  the  brain,  nerves,  yolk  of  eggs,  etc.,  ia 
primarily  the  substance  discovered  in  1864  by  Liebreich,  in  the  brail 
and  termed  l»rotagon.    It  is  a  white  crystallized  body,  having  the 
following  composition : 

Carbon,  67.2 

Hydrogen,       11.6 

Nitrogen,  2.7 

Phosphorus,      1.5 

Oxygen,          17.0 

100.0 

Its  formula  is  Cn8,  H241,  N4,  P,  022-  When  heated  to  the  boiling  point 
it  is  decomposed,  and  yields  among  other  products  glycerin,  phosphor 
ic  acid,  and  stearic  acid.  (Ann.  Ch.  Ph.,  134,  p.  30;. 

Saponification. — The  fats  are  characterized  by  forming 
Boaps  when  heated  with  strong  potash  or  soda-lye.  They 
are  by  this  means  decomposed,  an<!  give  rise  to  fatty 
acids*  which  remain  combined  with  the  alkalies,  and  to 
glycerin,  a  kind  of  liquid  sugar. 

EXP.  41. — Heat  a  bit  of  tallow  with  strong  solution  of  caustic  potash 
until  it  completely  disappears,  and  a  soap,  soluble  in  water,  is  obtained. 
To  one-half  the  hot  solution  of  soap,  add  chlorhydric  acid  until  the 
latter  predominates.  An  oil  will  separate  which  gathers  at  the  top  of 
the  liquid,  and  on  cooling,  solidifies  to  a  cake.  This  is  not,  however, 
the  original  fat.  It  has  a  different  melting  point,  and  a  different  chemi 
cal  composition.  It  is  composed  of  one  or  several  fatty  acids,  corre 
sponding  to  the  elementary  fats  from  which  it  was  produced. 

When  saponified  by  the  action  of  potash,  stearin  yields 
stearic  acid,Clt  H38O2;  palmitin  yields  palmitic  acid, 
C18  H33  Oa ;  and  olein  gives  oleic  acid,  C18  H34  O2.  The 
so-called  stearin  candles  are  a  mixture  of  stearic  and 
palmitic  acids.  The  glycerin,  C3  H8  O3,  that  is  simulta 
neously  produced,  remains  dissolved  in  the  liquid.  Glyce 
rin  is  now  found  in  commerce  in  a  nearly  pure  state,  as  a 
^olorleLS,  syrupy  liquid,  having  a  pleasant  sweet  taste. 

The  chemical  act  of  saponification  consists  in  the  re-arrangement 
of  the  elements  of  one  molecule  of  fat  and  three  molecules  of  water  in 
to  three  molecules  of  fatty  acid,  and  one  molecule  of  glycerin. 

Palmitin  Water.  Palmitic  acid.  Glycerin. 

/:i;  H,,  O,     +    3  (H,  O)    —    3(0,.    Hs,    O.^    +    C,    H8(V 


94  HOW   CROPS   GROW 

Saponification  is  likewise  effected  by  the  influence  of  strong  acids  and 
by  heating  with  water  alone  to  a  temperature  of  near  400°  F. 

Ordinary  soap  is  nothing  more  than  a  mixture  of  stearate,  palmtate, 
and  oleate  of  potash  of  soda,  with  or  without  glycerin.  Com  men  soft 
soap  consists  of  the  potash-compounds  of  the  above-named  acids,  mixed 
with  glycerin  and  water.  Hard  soap  is  usually  the  corresponding 
soda-compound,  free  from  glycerin.  When  soft  potash-soap  is  boiled 
with  common  salt  (chloride  of  sodium),  hard  soda-soap  and  chloride  of 
potassium  are  formed  by  transposition  of  the  ingredients.  On  cooling, 
soda-soap  forms  a  solid  cake  upon  the  liquid,  and  the  glycerin  remains 
dissolved  in  the  latter. 

Relations  of  Fats  to  Amyloids.  —  The  oil  or  fat  of 
plants  is  in  many  cases  a  product  of  the  transformation  of 
starch  or  other  member  of  the  cellulose  group,  for  the  oily 
seeds,  when  immature,  contain  starch,  which  vanishes  as 
they  ripen,  and  in  the  sugar-cane  the  quantity  of  wax  is 
said  to  be  largest  when  the  sugar  is  least  abundant,  and 
vice  versa.  In  germination  the  oil  of  the  seed  is  con 
verted  back  again  into  starch,  sugar,  etc. 

The  Estimation  of  fat  (including-wax)  is  made  by  warming  the  pulver 
ized  and  dry  substance  repeatedly  with  reaewpd  quantities  of  ether,  or 
sulphide  of  carbon,  as  long  as  the  solvent  takes  ip  anything.  On  evap 
orating  the  solutions,  the  fat  remains  nearly  in  a  state  of  purity,  and 
after  drying  thoroughly,  may  be  weighed. 

PROPORTIONS    OF   FAT   IN   VARIOUS    VEGETABLE    PRODUCTS. 


Per  cent. 

Meadow  grass 0.8 

Red  clover  (green) 0.7 

Cabbage 0.4 

Meadow  hay 3.0 

Clover  hay 3.2 

Wheat  straw 1.5 

Oat  straw 2.0 

Wheat  bran...  ..1.5 


Psr  cent. 

Turnip 0.1 

Wheat  kernel 1.6 

Oat  "       1.6 

Maize        "      7.0 

Pea  "       3.0 

Cotton  seed 34.0 

Flax          "  84,0 

Colza         "  ..  ...45.0 


Potato  tuber 0.3 

6,  THE  ALBUMINOIDS  OR  PROTEIN  BODIES. — The  bodies 
of  this  class  differ  from  the  groups  hitherto  noticed  in 
tKc  fact  of  their  containing  in  addition  to  carbon,  oxygen, 
and  hydrogen,  15  to  IS  per  rent  of  iit'troyeM,  with  a  small 
quantity  of  sulphur,  and,  in  sonic  cases,  phosphoric*. 


THE  VOLATILE  PART  OF  PLANTS.  95 

In  plants,  the  Protein  Bodies  occur  in  a  variety  of  modi- 

ficationsTand  though  found  in  small  proportion  in  all  their 

J/  parts,  being  everywhere  necessary   to  growth,  they  are 

l  chiefly  accumulated  in  the^seeds,  especially  in  those  of 

'  the  cereal:  and  leguminous  grains. 

The  albuminoids,  as  we  shall  designate  them,  that  oc 
cur  in  plants,  are  so  similar  in  many  characters,  are,  in 
fact,  so  nearly  identical  with  the  albuminoids  which  con 
stitute  a  large  portion  of  every  animal  organism,  that  we 
may  advantageously  consider  them  in  connection. 

We  may  describe  the  most  of  these  bodies  under  three 
sub-groups.  The  type  of  the  first  is  albumin,  or  the 
white  of  egg;  of  the  second, fibrin,  or  animal  muscle;  of 
the  third,  casein,  or  the  curd  of  milk. 

Common  Characters. — The  greater  number  of  these 
substances  occur  in  several,  at  least  two,  modifications, 
one  soluble,  the  other  insoluble  in  water. 

In  living  or  imdccayod  animals  and  plants  we  find  the 
albuminoids  in  the  soluble*  and,  in  fact,  in  the  dissolved 
state.  They  may  be  obtained  in  the  solid  form  by  evap 
orating  off  at  a  gentle  heat  the  water  which  is  naturally 
associated  with  them.  They  are  thus  mostly  obtained  as 
transparent,  colorless  or  yellowistiLSQlids,  destitute  of  odor 
or  taste,  whiclr~dissolve  again  in  water,  but  are  insoluble 
in  alcohol. 

Recently,  both  in  the  animal  and  vegetable,  soluble  al 
buminoids  have  been  observed  in  colorless  or  red  crystals, 
(or  crystalloids,)  often  of  considerable  size,  but  so  asso 
ciated  with  other  bodies  as,  in  general,  not  to  admit  of  sep- 
wation  in  the  pure  state. 

The  insoluble  albuminoids,  some  of  which  also  occur 
naturally  in  plants  and  animals,  are,  when  purified  as  much 
as  possible,  white,  flocky,  lumpy  or  fibrous  bodies,  quite 
odorless  and  tasteless. 

As  further  regards  the  deportment  of  the  albuminoids  towards  sol- 
venU,  some  are  dissolved  in  alcohol,  none  in  ether.  They  are  soluble  in 


96  HOW   CEOPS    GROW. 

potash  and  soda-lye ;  acids  separate  them  from  these  solutions,  strciig 
acetic  acid  dissolves  them  with  one  exception.  In  very  dilute  mineral 
acids  (sulphuric  and  chlorhydric)  some  of  them  dissolve  in  great  part, 
others  swell  up  like  jelly. 

:  Coagulation. — A  remarkable  characteristic  of  the  group 
of  bodies  now  under  notice  is  their  ready  conversion  from 
the  soluble  to  the  insoluble  state.  In  some  cases  this 
coagulation  happens  spontaneously,  in  others  by  elevation 
of  temperature,  or  by  contact  with  acids,  metallic  oxides, 
or  various  salts. 

The  albuminoids,  when  subjected  to  heat,  melt  and  burn 
with  a  smoky  flame  and  a  peculiar  odor — that  of  burnt 
hair  or  horn, — while  a  shining  charcoal  remains  which  is 
difficult  to  consume. 

Tests  for  tlie  Albuminoids. — The  chemist  employs  the 
behavior  of  the  albuminoids  towards  a  number  of  reagents*  as  tests 
for  their  presence.  Some  of  these  are  so  delicate  and  characteristic  as 
to  allow  the  distinction  of  this  class  of  substances  from  all  others,  even 
in  microscopic  observations. 
/  1.  Iodine  colors  them  intensely  yellow  or  bronze. 

2.  Warm  and  strong  cJdorJiydric  add  colors  all  these  bodies  blue  or 
Tiolet,  or,  if  applied  in  large  excess,  dissolves  them  to  a  liquid  of  these 
colors. 

•    3.  In  contact  with  nitric  acid  they  are  stained  a  deep  and  vivid  yellow.  . 
Silk  and  wool,  which  consist  of  bodies  closely  approaching  the  albumin 
oids  in  composition,  are  commonly  dyed  or  printed  yellow  by  means  of 
nitric  acid. 

4.  A  solution  of  nitrate  of  mercury  in  excess  of  nitric  acid,  f  tinges  ^V 
them  of  a  deep  red  color.  This  test  enables  us  to  detect  albumin,  for  \ 
example,  even  where  it  is  dissolved  in  100,000  parts  of  water. 

Albumin* — Animal  Albumin. — The  white  of  a  hen's 
egg  on  drying  yields  about  12  per  cent  of  albumin  in  a 
state  of  tolerable  purity.  The  fresh  white  of  egg  serves 

*  Reagents  are  substances  commonly  employed  for  the  recognition  of 
bodies,  or,  generally,  to  produce  chemical  changes.  All  chemical  phenomena  re- 
Bult  from  the  mutual  action  of  at  least  two  elements,  which  thus  act  and  react  on 
each  other.  Hence  the  substance  that  excites  chemical  changes  is  termed  a  re 
agent,  and  the  phenomena  or  results  of  its  application  are  called  reactions. 

t  This  solution,  known  as  Millon's  test,  is  prepared  by  dissolving  mercury 
in  its  own  weight  of  nitric  acid  of  ep.  gr.  1.4,  heating  towards  the  close  of  th« 
process,  ajid  finally  adding  to  the  liquid  twice  its  bulk  of  water. 


THE   VOLATILE   PART   OP   PLANTS.  9? 

to  illustrate  the  peculiarities  of  this  substance,  and  to  ex 
hibit  the  deportment  of  the  albuminoids  generally  towards 
the  above-named  reagents. 

Exr.  42. — Beat  or  whip  the  white  of  an  egg  so  as  to  destroy  the  deli 
cate  transparent  membrane  in  the  cells  of  which  the  albumin  is  held, 
aud  agitate  U  portion  of  it  with  water;  observe  that  it  dissolves  readily  in 
the  latter. 

EXP.  43. — Heat  a  p;xrt  of  the  undiluted  white  of  egg  in  a  tube  or  cup  I 
at  165°  F.;  it  becomes  opaque,  white,  and  solid,  (coagulates)  and  is  convert-  / 
ed  into  the  insoluble  modification.  A  higher  heat  is  needful  to  coagulate  I 
solutions  of  albumin,  in  proportion  as  they  are  diluted  with  water. 

EXP.  44. — Add  strong  alcohol  to  a  portion  of  the  solution  of  albumin 
of  Exp.  42.  It  produces  coagulation. 

EXP.  45.— Observe  that  albumin  is  coagulated  by  dilute  acids  applied 
In  small  quantity,  especially  by  nitric  acid. 

EXP.  46. — Put  a  little  albumin,  either  soluble  or  coagulated,  into  each 
of  four  test  tubes.  To  one,  add  solution  of  iodine  ;  to  a  second,  strong 
chlorhydric  acid;  to  a  third,  nitric  acid;  and  to  the  last,  nitrate  of 
mercury.  Observe  the  characteristic  colorations  that  appear  immedi 
ately,  or  after  a  time,  as  described  above.  In  the  last  three  cases  the 
reaction  is  hastened  by  a  gentle  heat. 

Albumin  occurs  in  the  soluble  form  in  the  blood,  and  in 
all  the  liquids  of  the  healthy  animal  body  except  the  urine. 
In  some  cases  its  characters  are  slightly  different  from 
those  of  egg-albumin.  The  albumin  of  the  blood,  which 
may  be  separated  by  heating  blood-serum  (the  clear 
yellow  liquid  that  floats  above  the  clot),  contains  a  little 
less  sulphur  than  coagulated  egg-albumin.  In  tpe  crystal 
line  lens  of  the  eye,  an-1  in  the  Mood  corpuscles,  the  al 
bumin  has  again  slightly  different  characters,  and  has  been 
termed  globulin.  Under  certain  conditions  the  blood  of 
animals  yields  a  substance  known  as  haemoglobin,  which, 
while  having  nearly  the  composition  and  many  of  the 
properties  of  albumin,  commonly  requires  a  much  larger 
proportion  of  water  for  solution,  and  forms  distinct  crys 
tals  of  a  transparent  red  color. 

Vegetable  Albumin. — In  the  juices  of  all  plants  is  found 
u  minute  quantity  of  a  substance  which  agrees  in  nearly 
all  respects  with  animal  albumin,  and  is  hence  termed 
5 


98  HOW   CROPS   GKOW. 

vegetable  albumin.  The  clear  juice  of  the  potato  tuber 
(which  may  be  procured  by  grating  potatoes,  squeezing 
the  pulp  in  a  cloth,  and  letting  th«  liquor  thus  obtained 
stand  in  a  cool  place  until  the  starch  has  deposited,)  con 
tains  albumin  in  solution,  as  may  be  shown  by  heating  to 
near  the  boiling  point,  when  a  coagulum  separates,  which, 
after  boiling  successively  with  alcohol  and  ether  to  remove 
fat  and  coloring  matters,  is  scarcely  to  be  distinguished, 
either  in  its  chemical  reactions  or  composition  from  the 
coagulated  albumin  of  eggs. 

The  juice  of  succulent  vegetables,  as  cabbage,  yields 
vegetable  albumin  in  larger  quantity,  though  less  pure,  by 
the  same  treatment. 

Water  which  has  been  agitated  for  some  time  in  contact 
with  flour  of  wheat,  rye,  oats,  or  barley,  is  found  by  the 
same  method  to  have  extracted  albumin  from  these  grains, 

The  corsgulnm,  thus  prepared  from  any  of  these  sources,  exhibits  the 
reactions  characteristic  of  the  albuminoids,  when  put  in  contact  with 
nitrate  of  mercury,  nitric  or  chlorhydric  acid;. 

EXP.  47. — Prepare  impure  vegetable  albumin  from  potatoes,  cabbage, 
or  flour,  as  above  described,  and  apply  the  nitrate  of  mercury  test. 

Fibrin. — Blood-Fibrin. — The  blood  of  the  higher  ani 
mals,  when  in  the  body  or  when  fresh  drawn,  is  perfectly 
fluid.  Shortly  after  it  is  taken  from  the  veins  it  partially 
solidifies  —  it  coagulates  or  becomes  clotted.  It  hereby 
separates  into  two  portions,  a  clear,  pale-yellow  liquid— 
the  serum,  and  the  clot.  As  already  stated,  the  serum 
contains  albumin.  The  clot  consists  chiefly  of  librm.  On 
squeezing  and  washing  the  clot  with  water,  the  coloring 
matter  of  the  blood  is  removed,  and  a  white  stringy  mass 
remains,  which  is  one  form  of  the  substance  in  question. 
Blood-fibrin  is  not  known  in  the  soluble  state,  except  in 
fresh  blood,  from  which  it  cannot  be  separated,  as  it  so 
soon  coagulates  spontaneously. 

Prepared  as  just  described,  fibrin  has  main  of  the  proper 
ties  of  albumin.  Clace_dJu_a.so]utiQii.of - 


Mf 

THE  VOLATILE  PART  OF  PLANTS.  99 

cially  if  a  little  potash  lye  be  added,  it  dissolves  in  a  few 
days  to  a  clear  liquid,  which  coagulated. on  heating  or  by. 
addition  of  metallic  salts,  in  the  same  manner  as  a  solu 
tion  of  albumin.  In  very  dilute  chlorhydric  acid,  it  swells 
uj>>  but  does  not  dissolve. 

EXP.  48. — Observe  the  separation  of  blood  into  clot  and  serum  ;  co 
agulate  the  albumin  of  the  former  by  heat,  and  test  it  with  warm  cbk  r- 
hydric  acid.  Tie  up  the  clot  in  a  piece  of  muslin,  and  squeeze  and  wash 
in  water  until  coloring  matter  ceases  to  run  off.  Warm  it  with  nitric 
iciti  as  a  test. 

Flesh-fibrin. — If  a  piece  of  lean  beef  or  other  meat  be 
repeatedly  squeezed  and  washed  in  water,  the  coloring 
matters  are  gradually  removed,  and  a  white  residue  is  ob 
tained,  which  resembles  blood-fibrin  in  its  external  char 
acters.  It  is,  in  fact,  the  actual  fibers  of  the  animal  muscle, 
and  hence  its  name.  It  is  characterized  by  dissolving  in 
very  dilute  chlorhydric  acid,  (one  part  acid  and  1,000  of 
water)  to  a  clear  liquid,  from  which  it  is  again  separated 
by  careful  addition  of  an  alkali,  or  a  solution  of  common 
salt. 

Vegetable-fibrin. — When  wheat-flour  is  mixed  with  a 
little  water  to  a  thick  dough,  and  this  is  washed  and 
.kneaded  for  some  time  in  a  vessel  of  water,  the  starch  and 
albumin  are  mostly  removed,  and  a  yellowish,  tenacious 
mass  remains,  which  bears  the  name  gluten.  When  wheat 
is  slowly  chewed,  the  saliva  carries  off  the  starch  and  other 
matters,  and  the  gluten  mixed  with  bran  is  left  behind — 
well-known  to  country  lads  as  "  wTheat-gum." 

EXP  i9.— Wet  a  handful  of  good,  fresh,  wheat  flour  slowly  with  a  lit 
tle  water  to  a  sticky  dough,  and  squeeze  this  under  a  fine  stream  of 
water  until  the  latter  rmis  off  clear.  Heat  a  portion  of  this  gluten  with 
Millon's  test. 

I     Gluten  is  a  mixture  of  several  albuminoids,  and  contains 
besides  some  starch  and  fat.     Vegetable-fibrin  is  dissolved 
from  it  by  alcohol,  and  separates  on  removing  the  alcohol 
by  evaporation. 
The  albuminoids  of  crude  gluten  dissolve  in  very  dil  ite  potash-lye 


100  HOW   CROPS   GROW. 

(one  to  one  and  one-half  parts  potash  to  1000  parts  of  water),  and  the 
liquid,  after  standing  some  days  at  rest,  may  be  poured  off  from  any 
residue  of  starch.  On  adding  acetic  acid  in  slight  excess,  the  purified 
albuminoids  are  separated  in  the  solid  state.  By  extracting  succes 
sively  with  weak,  with  strong,  and  with  absolute  alcohol,  a  form  of 
casein  (gluten-casein,  of  Rl'ithausen)  remains  tmdissolved,  which  is  perhaps 
identical  with  the  iasein  (legumin)  of  the  pea. 

On  evaporating  "he  alcoholic  solution  to  one-half,  there  separates,  on 
cooling,  a  brownish-yellow  mass.  This,  when  treated  with  absolute  al 
cohol,  leaves  vegetable-fibrin  nearly  pure. 

Vegetable-fibrin  is  readily  soluble  in  hot  alcohol,  but 
slightly  so  in  cold  alcohol.  It  does  not  at  all  dissolve  in- 
water.  It  has  no  fibrous  structure  like  animal  fibrin,  but 
forms,  when  dry,  a  tough,  horn-like  mass.  In  composition 
it  approaches  animal-fibrin. 

Casein* — Animal  casein  is  the  peculiar  ingredient  of 
new  cheese,  It  exists  dissolved  to  the  extent  of  3  to  6 
per  cent  in  fresh  milk,  unlike  albumin  is  not  coagulated! 
by  heat,  but  is  coagulated  by  acids,  by  rennet,  (the  meml 
brane  of  the  calf's  stomach),  and  by  heating  to  boiling 
with  salts  of  lime  and  magnesia. 

EXP.  50. — Observe  the  coagulation  of  casein  when  milk  is  treated 
with  a  few  drops  of  sulphuric  acid.  Test  the  curd  with  nitrate  of 
mercury. 

EXP.  51. — Boil  milk  with  a  little  sulphate  of  magnesia  (epsom  salts) 
until  it  curdles. 

When  casein  is  separated  from  milk  by  rennet,  as  in 
making  cheese,  it  carries  with  it  a  considerable  portion  of 
the  phosphates  and  other  salts  of  the  milk ;  these  salts 
are  not  found  in  the  casein  precipitated  by  acids,  being 
held  in  solution  by  the  latter. 

The  casein  of  milk  coagulates  spontaneously  when  it 
stands  for  some  time.  Casein  has  recently  been  detected 
in  the  brain  of  animals.  (Hoppe-Seyler,  Med.  Chem.  Un- 
ters.,  II.) 

Vegetable  casein. — This  substance  is  found  in  large  pro 
portion  (17  to  19  per  cent)  in  the  pea  and  bean,  and  in 
deed  generally  in  the  seeds  of  the  so-called  leguminous 
plants.  It  closely  r«  sembles  milk-casein  in  all  respects. 


THE  VOLATILE  PART  OF  PLANTS.          1  01 


52.  —  Prepare  a  solution  of  vegetable  casein  from  crushed  peas, 
oats,  almonds,  or  pea-nuts,  by  soaking  them  for  some  hours  in  warm 
water,  and  allowing  the  liquid  to  settle  clear.  Coagulate  the  casein  by 
addition  of  an  acid  to  the  solution.  It  may  be  coagulated  by  rennet, 
and  by  salts  of  magnesia  and  lime,  in  the  same  manner  as  animal  casein. 

The  Chinese  prepare  a  vegetable  cheese  by  boiling  peas 
to  a  pap,  straining  the  liquor,  adding  gypsum  until  coagu 
lation  occurs,  and  treating  the  curd  thus  obtained  in  the 
same  manner  as  practiced  with  milk-cheese,  viz.:  salt 
ing,  pressing,  and  keeping  until  the  odor  and  taste  of 
cheese  are  developed.  It  is  cheaply  sold  in  the  streets  of 
Canton  under  the  name  of  Tao-foo.  Vegetable  casein 
I  occurs  in  small  quantity  in  oats,  the  potato,  and  many 
plants  ;  and  may  be  exhibited  by  adding  a  few  drops  of 
acetic  acid  to  turnip  juice,  for  instance,  which  has  been 
freed  from  albumin  by  boiling  and  filtering.  The  casein 
from  peas  and  leguminous  seeds  has  been  designated 
legumin,  that  of  the  oat  has  been  named  avenin.  Almonds 
yieW~rr~casein,  which  has  been  termed  emulsin.  As  al 
ready  mentioned,  casein  (Ritthausen's  gluten-casein)  exists 
in  wheat-gluten,  and  in  rye.  Each  of  these  sources  yields 
a  casein  of  somewhat  peculiar  characters  ;  the  causes  of 
these  differences  are  not  yet  ascertained,  but  probably  lie 
in  impurities,  or  result  from  mixture  of  other  albuminoids. 

In  crude  wheat-gluten  two  other  albuminoids  exist,  viz.  : 

Giiadin,  or  vegetable  glue,  is  very  soluble  in  water  and 
alcohol.  It  strongly  resembles  animal  glue. 

Mucidin  resembles  gliadin,  but  is  less  soluble  in  strong 
alcohol,  and  is  insoluble  in  water.  When  moist,  it  is  yel 
lowish-white  in  color,  has  a  silky  luster,  and  slimy  consist 
ence.  It  exists  also  in  rye  grain.  (Ritthausen,  Jour,  far 
Prakt.  Chem.,  88,  141  ;  and  99,  463.) 

Composition  of  the  Albuminoids.  —  There  are  various 
reasons  why  the  exact  composition  of  the  bodies  just  de 
scribed  is  a  subject  of  uncertainty.  They  are,  in  the  first 
place,  naturally  mixed  and  associated  with  other  matter 


102  HOW   CEOPS   GEOW. 

from  winch  it  is  very  difficult  to  separate  them  fully. 
Again,  if  we  succeed  in  removing  foreign  substances,  it 
must  usually  be  done  by  the  aid  of  acids,  alkalies,  and 
other  strong  reagents,  which  easily  alter  or  destroy  their 
proper  characters  and  composition.  Finally,  if  we  analyze 
the  pure  substances,  our  methods  of  analysis  are  perhaps 
scarcely  delicate  enough  to  indicate  their  differences  with 
entire  accuracy. 

The  results  of  chemical  investigation  demonstrate  that 
the  albuminoids  are  either  identical  in  composition  or 
differ  but  slightly  from  each  other,  as  is  seen  from  the 
Table  below.  The  deduction  of  a  correct  atomic  formula 
from  these  analyses  is  perhaps  impossible  in  the  present 
state  of  our  knowledge. 

In  the  subjoined  Table  are  given  analyses  of  the  albuminoids 
which  have  been  described.  Those  indicated  by  asterisks  are  recent  re 
sults  of  Dr.  Ritthausen ;  the  others  are  average  statements  of  the  best 
analyses,  (after  Gorup-Besanez,  Org.  Chemie,  p.  611.) 

COMPOSITION     OF     ALBUMINOIDS. 

Carbon.  Hydrogen.  Nitrogen.  Oxygen.  Sulphur. 

Animal  albumin 53.5  7.0  15.5  22.4  1.6 

Vegetable  albumin....  53.4  7.1  15.6  23.0  0.9 

Blood  fibrin 52.6  7.0'  17.4  21.8  1.2 

Flesh  fibrin 54.1  7.3  16.0  21.5  1.1 

Wheat  fibrin* 54.3  7.2  16.9  20.6  1.0 

Animal  casein 53.6  7.1  15.7  22.6  1.0 

Vegetable  casein 50.5  6.8  18.0  24.2  0.5 

Gluten-casein*"]  51.0  6.7  16.1  25.4  0.8 

Gliadin*            [wheat  52.6  7.0  18.1  21.5  0.8 

Mucedin*         j 54.1  6.9  16.6  21.5  0.9 

Phosphorus  is  not  included  in  the  above  table,  for  the  reason  that  ID 
all  cases  its  quantify,  and  in  most  instances  its  very  presence,  is  still  un 
certain.  Voelcker  and  Norton  found  in  vegetable  casein  1.4  to  2.3  per 
cent  of  phosphorus,  and  smaller  quantities  have  been  mentioned  by 
other  of  the  older  analysts  as  occurring  in  albumin  and  fibrin.  The 
phosphorus  of  these  and  of  animal  casein  is  thought  not  to  belong  to 
the  albuminoid,  but  to  be  due  to  an  admixture  of  phosphate  of  lime. 

In  his  recent  investigation  of  gluten-casein,  Ritthausen  found  phos 
phoric  acid  that  appears  to  have  been  partially  uncombined  with  a  fixed 
base,  and  to  have  therefore  resulted  from  phosphorus  in  organic  eombi 


THE  VOLA.TILI  PAKT  OF  PLANTS.          103 

nation.  It  is  not  unlikely  that  -\cgetable  casein  may  contain  an  admix 
ture  of  pj  otaffon  (p.  93),  or  the  products  of  its  decomposition,  from 
which  it  is  not  easy  to  procure  a  separation. 

Mutual  Relations  of  the  Albuminoids.  —  Some  have 
supposed  that  these  bodies  are  identical  in  composition, 
the  differences  among  the  analytical  results  being  due  to 
foreign  matters,  and  differ  from  each  other  in  the  samej 
way  that  cellulose  and  starch  differ,  viz. :  on  account  of 
different  arrangement  of  the  atoms.  Others  formerly 
adopted  the  notion  of  Mulder,  to  the  effect  that  the  albu 
minoids  are  compounds  of  various  proportions  of  hypothet 
ical  sulphur  and  phosphorus  compounds,  with  a  common 
ingredient,  which  he  termed  protein,  (from  the  Greek  sig 
nifying  "to  take  the  first  place,"  because  of  the  great 
physiological  importance  of  such  a  body.)  Hence  the 
Albuminoids  are  often  called  the  protein-bodies.  The  trans 
formations  which  these  substances  are  capable  of  under 
going,  sufficiently  show  that  they  are  closely  related,  with 
out,  however,  satisfactorily  indicating  in  what  manner. 

In  the  animal  organism,  the  albuminoids  of  the  food,  of 
whatever  name,  are  dissolved  in  the  gastric  juice  of  the 
stomach,  and  pass  into  the  blood,  where  they  form  blood- 
albumin  and  blood-fibrin.  As  the  blood  nourishes  the 
muscles,  they  are  modified  into  flesh-fibrin,  or  entering  the 
lacteal  system,  are  converted  into  casein,  while  in  the  ap 
propriate  part  of  the  circulation  they  are  formed  into  the 
albumin  of  the  egg,  or  embryo. 

In  the  living  plant,  similar  changes  of  place  and  of  char 
acter  occur  among  these  substances. 

Finally,  outside  the  organism  the  following  transforma 
tions  have  been  observed :  Flesh-fibrin  exposed  while 
moist  to  the  air  at  a  sumn  er  temperature  for  some  days, 
dissolves  into  a  liquid ;  it  this  liquid  be  heated  to  near 
boiling,  coagulation  takes  place,  and  the  substance  which 
separates  has  the  properties  of  albumin.  On  removing 
the  albumin  and  adding  vinegar  to  the  remaining  liquid, 


104  HOW   CROPS   GROW. 

a  curdy  coagulumis  formed,  which  agrees  in  its  properties 
with  casein.  (Bopp,  Ann.  Gh.  Ph.,  60,  p.  30 ;  Gunning, 
Jour,  fur  Prakt.  Chem.,  69,  p.  52.) 

Lehmann  has  shown  that  when  albumin  is  dissolved  in 
potash,  and  mixed  with  a  little  milk-sugar  and  oily  fat,  the 
mixture  coagulates  with  rennet  exactly  as  milk  curdles. 
(Gorup-Besanez,  Phys.  Chem.,  p.  139.) 

Sullivan  has  observed  that  the  casein  of  milk  which  waa 
kept  in  closed  air-tight  vessels  for  a  long  time,  at  first  co 
agulated,  but  afterward  dissolved  again  to  a  nearly  clear 
liquid,  which  was  found  to  contain  no  casein,  but  by  heat 
ing,  coagulated,  showing  the  conversion  of  casein  into 
albumin,  or  a  similar  body.  (Phil.  Mag.,  4,  XVIII,  203.) 

Some  maintain  that  casein  is  not  a  distinct  albuminoid, 
but  a  compound  of  albumin  with  potash,  containing,  ac 
cording  to  Lieberkiihn,  5.5°|  0  of  this  alkali.  Its  peculiarities 
are  in  part  due  to  its  natural  association  with  phosphate 
of  potash.  Kiihne,  Phys.  Chem.,  1868,  p.  565.  See,  how 
ever,  Schwarzenbach,  Ann.  Ch.  u.  Ph.,  144,  p.  63. 

The  Albuminoids  in  Animal  Nutrition. — We  step 
aside  for  a  moment  from  our  proper  plan  to  direct  atten 
tion  to  the  beautiful  adaptation  of  this  group  of  organic 
substances  to  the  nutrition  of  animals.  Those  bodies  which 
we  have  just  noticed  as  the  animal  albuminoids,  together 
with  others  of  similar  composition,  constitute  a  large  share 
of  the  healthy  animal  organism,  and  especially  characterize 
its  actual  working  machinery,  being  essential  ingredients 
of  the  muscles  find  cartilages,  as  well  as  of  the  nerves  and 
brain.  They  likewise  exist  largely  in  the  nutritive  fluids 
of  the  animal — in  blood  and  milk.  So  far  as  we  know,  :he  ~1 
animal  body  has  not  the  power  to  produce  a  particle  of 
albumin,  or  fibrin,  or  casein;  it  can  only  transform  these"7 
bodies  as  presented  to  it  from  external  sources.  They  are 
hence  indispensable  ingredients  of  food,  and  have  been 
aptly  designated  by  Liebig  as  the  plastic  elements  of  nu 
trition.  It  is,  in  all  cases,  the  plant  which  originally  con- 


THE  VOLATILE  PART  OF  PLANTS.  105 

structs  these  substances,  and  places  them  at  the  disposal 
of  the  animal. 

The  albuminoids  are  mostly  capable  of  existing  in  the 
liquid  or  soluble  state,  and  thus  admit  of  distribution 
throughout  the  entire  animal  body,  as  blood,  etc.  They 
likewise  readily  assume  the  solid  condition,  thus  becoming 
more  permanent  parts  of  the  living  organism,  as  well  as 
capable  of  indefinite  preservation  for  food  in  the  seeds  and 
other  edible  parts  of  plants. 

Complexity  of  Constitution. — The  albuminoids  are  high 
ly  complex  in  their  chemical  constitution.  This  fact  is 
shown  as  well  by  the  multiplicity  of  substances  which  may 
be  produced  from  them  by  destructive  and  decomposing 
processes,  as  by  the  ease  with  which  they  are  broken  up 
into  other  and  simpler  compounds.  Subjected  in  the  solu 
ble  or  moist  state  to  the  action  of  warm  air,  they  speedily 
decompose  or  putrefy,  yielding  a  large  variety  of  products. 
Heated  with  acids,  alkalies,  and  oxidizing  agents,  they  all 
give  origin  to  the  same  or  to  analogous  products,  among 
which  no  less  than  twenty  different  compounds  have  been 
distinguished. 

Occurrence  in  Plants — Aleurone. — It  is  only  in  the  old 
and  virtually  dead  parts  of  a  living  plant  that  albuminoids 
are  ever  wanting.  In  the  young  and  growing  organs  they 
are  abundant,  and  exist  dissolved  in  the  sap  or  juices. 
They  are  especially  abundant  in  seeds,  and  here  they  are 
deposited  in  an  organized  form,  chiefly  in  grains  similar  to 
those  of  starch,  and  are  nearly  or  altogether  insoluble  in 
water. 

These  grains  of  albuminoid  matter  are  not,  in  many 
cases  at  least,  pure  albuminoids.  They  appear  to  contain 
vegetable  albumin,  casein,  fibrin,  etc.,  associated  together, 
though,  in  general,  casein  and  fibrin  are  largely  predomi 
nant.  Hartig,  who  first  described  them  minutely,  has  dis 
tinguished  them  by  the  name  aleurone,  a  term  which  we 
may  conveniently  employ.  By  the  word  aleurone  ,43  not 
5* 


106 


HOW    CROPS    GHOW. 


meant  simply  an  albuminoid,  or  mixture  of  albuminoids, 
but  the  organized  granules  found  in  the  plant,  of  which 
the  albuminoids  are  chief  ingredients. 

In  Fig.  18  is  represented  a  magnified  slice  through  the 
outer  cells,  (bran,)  of  a  husked  oat  kernel.  The  cavities 
of  these  outer  cells,  a,  c,  are  chiefly  occupied  with  very 


Fig.  19. 

fine  grains  of  aleurone,  (casein.)  In  one  cell,  b^  are  seen 
the  much  larger  starch  grains.  In  the  interior  of  the  oat 
kernel  and  other  cereal  seeds,  the  cells  are  chiefly  occupied 
with  starch,  but  throughout  grains  of  aleurone  are  more 
or  less  intermingled. 

Fig.  19  exhibits  a  section  of  the  exterior  part  of  a  flax- 
seed.  The  outer  cells,  «,  contain  vegetable  mucilage ;  the 
interior  cells,  e,  are  mostly  filled  with  minute  grains  of 
aleurone,  among  which  droplets  of  oil,/",  are  distributed. 

In  Fig.  20  are 
shown  some  of  the 
forms  assumed  by  in 
dividual  albuminoid- 
grains  ;  a  is  aleurone 
from  the  seed  of  the  vetch,  b  from  the  castor  bean,  c 
from  flax-seed,  d  from  the  fruit  of  the  bayberry,  (Myrica 


THE    VOLATILE    PA11T    OF    PLANTS. 


107 


ra,)  and  <?  from  mace,  (an  appendage  to  the  nutmeg, 
or  fruit  of  the  Myristica  moschata.) 

Crystalloid  aleurone. — It  has  been  already  remarked 
that  crystallized  albuminoids  may  be  obtained  from  the 
blood  of  animals.  It  is  equally  true  that  bodies  of  similar 
character  exist  in  plants,  as  was  first  observed  by  Hartig, 
(E)itwickelungsgeschichte  des  PflanzenJceims,  p.  104.)  In 
form  they  sometimes  imitate  crystals  quite  perfectly,  Fig. 
21,  a  ;  in  other  cases,  &,  they  are  rounded  masses,  having 
some  crystalline  planes  or  facets.  They  are  soft,  yield 
easily  to  pressure,  swell  up  to  double  their  bulk  when 


Fig.  21. 

soaked  in  weak  acids  or  alkalies,  and  their  angles  have 
none  of  the  constancy  peculiar  to  proper  crystals.  There 
fore  the  term  crystalloid,  i.  e.  having  the  likeness  of  crys 
tals,  is  more  appropriate  than  crystallized. 

As  Cohn  first  noticed,  (Jour,  far  Pmkt.  Chem.,  80, 
p.  129,)  crystalloid  aleurone  may  be  observed  in  the  outer 
portions  oTthe  potatb"Turj>er,  in  which  it  invariably  pre 
sents  a  cubical  form.  It  is  best  found  by  examining  the 
cells  that  adhere  to  the  rind  of  a  potato  that  has  been 
boiled.  In  Fig.  21,  a  represents  a  cell  from  a  boiled  pota 
to,  in  the  centre  of  which  is  seen  the  cube  of  aleurone. 
It  is  surrounded  by  the  exfoliated  remnants  of  starch- 
grains.  In  the  same  figure,  b  exhibits  the  contents  of 
a  cell  from  the  seed  of  the  bur  reed,  (Sparganium  ramo- 
sum,)  a  plant  that  is  common  along  the  borders  of  ponds. 
In  the  center  is  a  comparatively  large  mass  of  aleurone, 
having  crystalloid  facets. 


108  HOW   CEOPS   GROW. 

According  to  Haschke,  (Jour,  fur  Pr.  Ch>  79,  p.  148,) 
the  crystalloid  aleurone  that  is  abundant  in  the  Brazil 
nut,  is  a  compound  of  casein  with  some  acid  of  unknown 
composition.  This  aleurone  may  be  dissolved  in  water, 
and  recovered  in  its  original  form  on  evaporation. 

Kubel's  analysis  of  aleurone,  prepared  from  the  Brazil 
nut  by  Hartig,  gave  its  content  of  nitrogen  9.46  per  cent. 
Aleurone  from  the  yellow  lupin  yielded  him  9.26  per  cent. 
Since  pure  casein  'has  16  to  18  per  cent  of  nitrogen,  the 
aleurone  contained  about  52  to  59  per  cent  of  albuminoids. 

Estimation  of  the  Albuminoids. — The  quantitative  sep 
aration  of  these  bodies  is  a  matter  of  groat  difficulty  and 
uncertainty.  For  most  purposes  their  collective  quantity 
in  any  organic  substance  may  be  calculated  with  sufficient 
accuracy  from  its  content  of  nitrogen.  All  the  albumin 
oids  contain,  on  the  average,  about  J. 6 per  cent^ of  nitrogen. 
This  divided  into  100  gives  a  quotient  of  6.25.  If,  now, 
the  percentage  of  nitrogen  that  exists  in  a  given  plant  be 
multiplied  by  6.25,  the  product  will  represent  its  percent 
age  of  albuminoids,  it  being  assumed  that  all  the  nitrogen 
of  the  plant  exists  in  this  form,  which  in  most  cases  is  prac 
tically  true. 

Frtthling  and  Grouven  have  recently  investigated  the 
condition  of  the  nitrogen  of  various  plants,  and  have  found 
that  nitric  acid,  (Na  OB,)  which  in  the  form  of  nitrate  of 
potash  has  long  been  known  to  occur  in  vegetation,  is 
present  in  but  trifling  quantity  in  most  agricultural  plants. 
In  mature  clover,  esparsette,  lucern,  wheat,  rye,  oats,  bar 
ley,  the  pea,  and  the  lentil,  it  did  not  exceed  2  parts  in 
10,000  of  the  air-dry  plant.  In  maize,  they  found  twice 
this  quantity ;  in  beet  and  potato  tops  alone  of  all  the  plants 
examined  was  nitric  acid  present  to  the  amount  of  four- 
tenths  of  one  per  cent,  (  Vs.  St.,  IX,  153.)  Salts  of  am 
monia  (N  Ha)  likewise  often  exist  in  plants,  but  as  a  rule 
in  quite  inconsiderable  quantities. 


THE    VOLATILE    PABT   OF   I.LANTS.  109 

kVBRAGE  QUANTITY  OP  ALBUMINOIDS  IN  VARIOUS  VEGETABLE  PRODUCT? 

per  cent. 

Maize  fodder,  green 1.2 

Beet  tops  "     1.9 

Carrot  tops          "     3.5 

Meadow  grass     "     3.1 

Red  clover          "     3.7 

White  clover       "     4.0 

Turnips,  fresh 1.0 

Carrots       "    1.3 

Potatoes     "    2.0 

Corn  cobs,  air-dry 1.4 

Straw  of  summer  grain,  air-dry 2.6 

Straw  of  winter         "          "      3.0 

Pea  straw  "      7.3 

Bean  straw  " 10.2 

Meadow  hay  •*      8.5 

Red  clover  hay  •'      13.4 

White  clover  hay  "      14.9 

Buckwheat  kernel  "      7.8 

Barley  "  "      10.0 

Maize  "  .    " 10.7 

Rye  "  "       11.0 

Oat  "  "      12.0 

Wheat  "  "      13.2 

Pea  "  "      22.4 

Bean  "  ««      24.1 

Lupine  "  «•      34.5 


APPENDIX    TO    §  4. 
CHLOROPHYLL  :  TANNIN  :  ALKALOIDS. 

Before  dismissing  the  subject  of  the  Proximate  Elements  of  plants,  we 
must  notice  several  other  substances  of  subordinate  agricultural  inter 
est.  Two  of  these,  viz.,  Chlorophyll  and  Tannin,  though  not  figuring  in 
the  analysis  of  agricultural  plants,  are  nevertheless  of  almost  universal 
occurrence  in  all  forms  of  vegetation,  though  usually  in  very  minute 
quantity. 

Chlorophyll,  i.  e.  leaf-green,  is  the  name  applied  to  the  substance 
which  occasions  the  green  color  in  vegetation.  It  is  found  in  all  the  sur 
face  of  annual  plants  and  of  the  annually  renewed  parts  of  perennial 
plants.  It  might  readily  be  supposed  that  it  constitutes  a  large  portion 
of  the  leaves  of  vegetation,  but  the  fact  is  quite  otherwise.  The  green 


110  HOW   CROPS   GROW. 

parts  of  plants  usually  contain  chlorophyll  only  at  their  bdrface,  and 
in  quantity  no  greater  than  colored  fabrics  contain  the  particles  of  dye. 

Chlorophyll  being  soluble  in  ether,  accompanies  fat  or  wax  when  these, 
are  removed  from  green  vegetable  matters  by  this  solvent.     It  is  soluola 
in  chlorhydric  and  sulphuric  acids,  imparting  to  these  liquids   its  in 
tense  green  color.    According  to  Pfaundler,  the  (impure  ?)  chlorophyll 
of  grass  has  the  following  percentage  composition  : 
Carbon       60.85 
Hydrogen     6.39 
Oxygen       32.78 

Fremj  has  shown  that  chlorophyll  may  be  easily  decomposed  into  two 
coloring  matters,  a  yellow,  Zaidhopliyll,  and  a  blue,  Cyanophyll.  This  ia 
accomplished  by  treating  chlorophyll  with  a  mixture  of  chlorhydric  add 
and  ether ;  the  cyanophyll  dissolves  in  the  latter,  and  the  zanthophyl'i  is 
taken  up  by  the  former  solvent.  The  yellow  color  of  autumn  leaves  is 
perhaps  due  to  zanthophyll. 

According  to  Sachs,  there  exists  in  those  parts  of  plants,  which,  though 
not  green,  are  capable  of  becoming  so,  a  colorless  substance,  Leucophyll, 
which,  in  contact  with  oxygen,  acquires  a  green  color,  being  converted 
into  chlorophyll. 

Tannin  is  the  general  designation  of  the  bitter,  astringent  prin 
ciples,  (used  in  leather-making,)  of  the  bark  and  leaves  of  the  hemlock, 
oak,  sumach,  plum,  pear,  and  many  other  trees,  of  tea,  coffee,  and  of 
gall-nuts.  It  is  found  in  small  quantity  in  the  young  bean  plant,  and  in 
many  germinating  seeds. 

Tannin  is  closely  related  to  the  carbohydrates,  as  is  demonstrated 
alike  by  the  microscopic  study  of  its  development  in  the  plant,  and  by 
our  knowledge  of  its  chemical  composition.  The  tannins  are  weak 
acids,  and  are  distinguished,  according  to  their  origin,  as  Oallotannic 
curid  (from  nut-galls),  Caffeotannic  acid  (from  coffee),  Quei'titannic  acid  • 
(from  the  oak),  etc.  As  already  hinted,  the  tannins  are  Glucovides,  orfl 
compounds  of  sugar,  with  some  other  substance  In  gall-tannin  the 
sugar  is  glucose,  and  the  substance  associated  with,  or  rather  yielded  by 
it  on  decomposition,  is  known  as  Gallic  acid.  By  boiling  gall-tannin 
with  a  dilute  acid,  or  by  subjecting  its  solution  to  fermentation,  decom 
position  into  the  two  substances  named  is  accomplished. 

According  to  Streckcr,  the  composition  of  gall- tannin  and  this  con 
version  are  indicated  by  the  following  formulae: 

Tannin.  Water.          Gallic  acid.  Glucose. 

2  (C27  H22  O17)  +  8  (H2  O)  =  6  (C,  H.  O6)  +  C,a  H24  O13 

THE  ALKALOIDS  are  a  class  of  bodies  very  numerous  in  poisonous  and 
medicinal  plants,  of  which  they  usually  constitute  the  active  principle. 
Those  which  have  an  agricultural  interest  are  Nicotin,  Caffein,  and 
Theobromin. 

I\icoliii,  C10  H14  N2,  is  the  narcotic  and  extremely  poisonous  prin 
ciple  in  tobacco,  where  it  exists  in  combination  with  malic  and  citric 


THE    ASH    OF   PLANTS.  Ill 

acids.  In  the  pure  state  it  is  a  colorless,  oily  liquid,  having  the  odoi 
of  tobacco  iu  an  extreme  degree.  It  is  inflammable  and  volatile,  and  so 
deadly  that  a  single  drop  will  kill  a  large  dog.  French  tobacco  contains 
7  or  8  p.  c.;  Virginia,  6  or  7  p.  c.;  and  Maryland  and  Havauna,  about  2 p. 
c.  of  nicotin.  Nicotin  contains  17.3  p.  c.  of  nitrogen,  but  no  oxygen. 

4/aiIoiu,  C8  H10  N4  O2,  exists  in  coffee  and  tea  combined  with  tannic 
\  acid.  In  the  pure  state  it  forms  white,  silky,  fibrous  crystals,  and  has  a 
\bitter  taste.  In  coffee  it  is  found  to  the  extent  of  one-half  per  cent ;  in 
(tea  it  occurs  in  much  larger  quantity,  sometimes  as  high  as  6  per  cent. 

rriieol>romiii,  C7  H8  N4  02,  resembles  caffeiu  in  its  characters, 
and  is  closely  related  to  it  in  chemical  composition.  It  is  found  in  the 
cacao-bean,  from  which  chocolate  is  manufactured. 

Thft_ajkj.loiti^^ire^miu-kai)lp,  from  containing  nitrogen,  and  from  hav 
ing  strongly  basic  characters.  They  derive  their  designation,  alkaloids, 
<'  MF  likeness  to  the  alkalies. 


CHAPTER     II 
THE    ASH    OF    PLANTS. 

§1- 

THE    INGREDIENTS    DF    THE    ASH. 

As  has  been  stated,  the  volatile  or  destructible  part  of 
plants,  i.  e.  the  part  which  is  converted  into  gases  or  vapors 
under  the  ordinary  conditions  of  burning,  consists  chiefly 
of  Carbon,  Hydrogen,  Oxygen,  and  Nitrogen,  together 
with  minute  quantities  of  Sulphur  and  Phosphorus. 
These  elements,  and  such  of  their  compounds  as  are  of 
general  occurrence  in  agricultural  plants,  viz.,  the  Organic 
Br,pximate  Principles,  have  been  already  described  in  detail. 
/  The  non-volatile  part  or  ash  of  plants  also  contains,  or 
may  contain,  Carbon,  Oxygen,  Sulphur,  and  Phosphorus. 
It  is,  however,  m  general,  chiefly  made  up  of  eight  other 
elements,  whose  common  compounds  are  fixed  at  the  or4i- 
nary  heat  of  burning. 


112  HOW   CEOPS   GBO\V. 

In  the  subjoined  table,  the  names  of  the  12  elements  of 
the  ash  of  plants  are  given,  and  they  are  grouped  under 
two  heads,  the  non-metals  and  the  metals,  by  reason  of  an 
important  distinction  in  their  chemical  nature. 

ELEMENTS  OF  THE  ASH  OF  PLANTS. 

Non-Metals.  Metals. 

Oxygen  .  .Potassium 

Carbon  Sodium 

Sulphur  Calcium 

Phosphorus  Magnesium 

Silicon  Iron 

Chlorine  Manganese 

If  to  the  above  be  added 

Hydrogen  and  Nitrogen 

the  list  includes  all  the  elementary  1mb stances  that  belong 
to  agricultural  vegetation. 

Hydrogen  is  never  an  ingredient  of  the  perfectly  burned 
and  dry  ash  of  any  plant. 

Nitrogen  may  remain  in  the  ash  under  certain  conditions 
in  the  form  of  a  Cyanide,  (compound  of  Carbon  and  Ni 
trogen,)  as  will  be  noticed  hereafter. 

Besides  the  above,  certain  other  elements  are  found,  either  occasion 
ally  in  common  plants,  or  in  some  particular  kind  of  vegetation  :  these 
are  Iodine,  Bromine,  Fluorine,  Titanium,  Arsenic,  Lithium,  Rubidium, 
Barium,  Aluminum,  Zinc,  Copper. 

We  may  now  complete  our  study  of  the  Composition 
of  the  Plant  by  attending  to  a  description  of  those  ele 
ments  that  are  peculiar  to  the  ash,  and  of  those  compounds 
which  may  occur  in  it. 

It  will  be  convenient  also  to  describe  in  this  section 
some  substances,  which,  although  not  ingredients  of  the 
ash,  may  exist  in  the  plant,  or  are  otherwise  important  to 
be  considered. 

The  non-metallic  elements,  which  we  shall  first  no 
tice,  though  differing  more  or  iess  widely  among  them 
selves,  have  one  point  of  resemblance,  viz.,  they  and  their 
compounds  with  each  other  have  acid  properties,  i.  e.  they 


THE    ASH    OF   PLANTS.  113 

either  arc  acids  in  the  ordinary  sense  of  being  sour  to  the 
taste,  or  enact  the  part  of  acids  by  uniting  to  metals  or 
metallic  oxides,  to  form  salts.  We  may,  there  tore,  desig- 
nate  them  as  the  acid  elements.  They  are  Oxygen,  Sulphur, 
Phosphorus,  Carbon,  Silicon,  and  Chlorine.  (Less  com 
mon  are  Arsenic,  Titanium,  Iodine,  Bromine,  and  Fluorine.) 

With  the  exception  of  Silicon,  (and  Titanium,)  and  the 
denser  forms  of  Carbon,  these  elements  by  themselves  are ' 
readily  volatile.     Their  compounds  with  each  other,  which 
may  occur  in  vegetation,  are  also  volatile,  with  two  ex-  • 
ceptions,  viz.,  Silicic  and  Phosphoric  acids. 

In  order  that  they  may  resist  the  high  temperature  at 
which  ashes  are  formed,  they  must  be  combined  with  the 
metallic  elements  or  their  oxides  as  salts. 

Oxygen,  Symbol  O,  atomic  weight  16,  is  an  ingredient 
cf  the  ash,  since  it  unites  with  nearly  all  the  other  elements 
of  vegetation,  either  during  the  life  of  the  plant,  or  in  the 
act  of  combustion.  It  unites  with  Carbon,  Sulphur,  Phos 
phorus,  and  Silicon,  forming  acid  bodies ;  while  with  the 
metals  it  produces  oxide_s,  which  have  the  characters  of 
bases.  Chlorine  alone  of  the  elements  of  the  plant  doea 
not  unite  with  oxygen,  either  in  the  living  plant,  or  during 
its  combustion. 


CAEEON     AND     ITS     COMPOUNDS. 


I1arl)0ll.  Sym.  C,  at.  wt.  12,  has  been  noticed  already 
with  sufficient  fulness,  (p.  31.)  It  is  often  contained  as 
charcoal  in  the  ashes  of  the  plant,  owing  to  its  being  en 
veloped  in  a  coating  of  fused  saline  matters,  which  shield 
it  from  the  action  of  oxygen. 

Carbonic  acid,  Sym.  C  O2,  molecular  weight,  44,  is  the 
colorless  gas  which  causes  the  sparkling  or  effervescence 
of  beer  and  soda  water,  and  the  frothing  of  yeast/ 

It  is  formed  by  the  oxidation  of  carbon,  when  vegetable 
matter  is  burned,  (Exp.  6.)  It  is,  therefore,  found  in  the 
ash  of  plants,  combined  with  those  bases  which  in  the  liv- 


114  HOW   CROPS   GROW. 

ing  organism  existed  in  union  with  organic  acids  ;  the  lat- 
tei  being  destroyed  by  burning. 

It  also  occurs  in  combination  with  lime  in  the  tissues  of 
many  plants.  Its  compounds  with  bases  are  carbonates 
to  be  noticed  presently.  When  a  carbonate,  as  marble  or 
limestone,  is  drenched  with  a  strong  acid,  like  vinegar  or 
muriatic  acid,  the  carbonic  acid  is  set  free  with  effer 
vescence 

Cyanogen,  Sym.  CN.—  This  important  compound  of  Carbon  and 
Nitrogen  is  a  gas  which  has  an  odor  resembling  that  of  peach-pits, 
and  which  burns  on  contact  with  a  lighted  taper  with  a  fine  purple  flame. 
In  its  union  with  oxygen  by  combustion,  carbonic  acid  is  formed,  and 
nitrogen  set  free, 


Cyanogen  may  be  prepared  by  heating  an  intimate  mixture  of  two  parts 
Ifty  weight  of  ferrocyanide  of  potassium,  (yellow  prussiate  of  potash,)  and 
three  parts  of  corrosive  sublimate.  The  operation  may  be  conducted  in 
a  test  tube  or  small  flask,  to  the  mouth  of  which  is  fitted  a  cork  pene 
trated  by  a  narrow  glass  tube.  On  applying  heat,  the  gas  issues,  and 
may  be  set  on  fire  to  observe  its  beautiful  flame. 

Cyanogen,  combined  with  iron,  forms  the  Prussian  blue  of  commerce, 
and  its  name,  signifying  the  blue-producer,  was  given  to  it  from  that  cir 
cumstance. 

Cyanogen  unites  with  the  metallic  elements,  giving  rise  to  a  series  of 
bodies  which  are  termed  Cyanides.  Some  of  these  often  occur  in  small 
quantity  in  the  ashes  of  plants,  being  produced  in  the  act  of  burning  by 
the  union  of  nitrogen  with  carbon  and  a  metal.  For  this  result,  the 
temperature  must  be  very  high,  carbon  must  be  in  excess,  the  metal 
is  usually  potassium  or  calcium,  the  nitrogen  may  be  either  free  nitrogen 
of  the  atmosphere  or  that  originally  existing  in  the  organic  matter. 

With  hydrogen,  cyanogen  forms  the  deadly  poison  hydrocyanic  oi'prus- 
sic  acid,  H  Cy,  which  is  produced  from  amygdaline,  one  of  the  ingre 
dients  of  bitter  almonds,  peach,  and  cherry  seeds,  when  these  are  crush 
ed  in  contact  with  water. 

When  a  cyanide  is  brought  in  contact  with  steam  at  high  temperatures, 
It  is  decomposed,  all  its  nitrogen  being  converted  into  ammonia. 

Cyanogen  is  a  normal  ingredient  of  one  common  plant  The  oil  of 
mustard  is  the  sulpho-cyanide  of  allyle,  C8  II8  CNS. 

SULPHUR  AND  ITS  COMPOUNDS. 

Sulphur,  Sym.  S,  at.  wt.  32.—  The  properties  of  this 
element  have  been  already  described,  (p.  42.)  Some  of 


THE    ASH    OF   PLANTS.  115 

its  compounds  have  also  been  briefly  alluded  to,  1  at  re 
quire  more  detailed  notice. 

Sulpliydric  Acid,  Sym  H2  S,  mo.  wt.  34.  This  substance,  fa 
miliarly  known  as  sulphuretted  hydrogen,  occurs  dissolved  in  the  water 
of  numerous  so-called  sulphur  springs,  as  those  of  Avon  and  Sharon,  N. 
Y.,  from  which  it  escapes  as  a  fetid  gas.  It  is  not  unfrequently  emitted 
from  volcanoes  and  fumaroles.  It  is  likewise  produced  in  the  decay  of 
organic  bodies  which  contain  sulphur,  especially  eggs,  the  intolerable 
odor  of  which,  when  rotten,  is  largely  due  to  this  gas.  It  is  evolved 
from  manure  heaps,  from  salt  marshes,  and  even  from  the  soil  of  moist 
meadows. 

The  ashes  of  plants  sometimes  yield  this  gas  when  they  are  moisten 
ed  with  water.  In  such  cases,  a  sulphide  of  potassium  or  calcium  has  been 
formed  in  small  quantity  during  the  incineration. 

Sulphydric  acid  is  set  free  in  the  gaseous  form  by  the  action  of  an  acid 
on  various  sulphides,  as  those  of  iron,  (Exp.  17,)  antimony,  etc.,  as  well  as 
by  the  action  of  water  on  the  sulphides  of  the  alkali  and  alkali-earth  metals. 
It  may  be  also  generated  by  passing  hydrogen  gas  into  melted  sulphur. 

Sulphuretted  hydrogen  has  a  slight  acid  taste.  It  is  highly  poisonous 
and  destructive,  both  to  animals  and  plants. 

Sulphurous  Acid,  Sym.  SO2,  mo.  wt.  64.  When  sulphur  is 
burned  in  the  air,  or  in  oxygen  gas,  it  forms  copious  white  suffocating 
fumes,  which  consist  of  one  atom  of  sulphur,  united  to  two  atoms  of 
oxygen;  S  02,  (Exp.  15.) 

Sulphurous  acid  is  characterized  by  its  power  of  discharging,  for  a  time 
at  least,  most  of  the  red  and  blue  vegetable  colors.  It  has,  however,  no 
action  on  many  yellow  colors.  Straw  and  wool  are  bleached  by  it  in  the 
arts. 

Sulphurous  acid  is  emitted  from  volcanoes,  and  from  fissures  in  the 
soil  of  volcanic  regions.  It  is  produced  when  bodies  containing  sulphur 
are  burned  with  imperfect  access  of  air,  and  is  thrown  into  the  atmos 
phere  in  large  quantities  from  fires  which  are  fed  by  mineral  coal,  as  well 
as  from  the  numerous  roasting  heaps  of  certain  metallic  ores,  (sulphides,) 
which  are  wrought  in  mining  regions. 

Sulphurous  acid  may  unite  with  bases,  yielding  salts  known  as  sul 
phites,  some  of  which,  viz.,  sulphite  of  lime  and  sulphite  of  soda,  are  em 
ployed  to  check  or  prevent  fermentation,  an  effect  also  produced  by  the 
ucid  itself. 

Anhydrous*  Sulphuric  Acid,  Sym.  SOS,  mo.  wt.  80,  is 

known  to  the  chemist  as  a  white,  silky  solid,  which  attracts 
moisture  with  great  avidity,  and,  when  thrown  into  water, 
hisses  like  a  hot  iron,  forming  the  hydrated  sulphuric  acid. 

*  i. «.,  free  from  water. 


116  HOW    CROPS    GROW. 

Hydrated  Sulphuric  Acid,  Sym.  Ha  O  SO3  or  H2  SOv, 

mo.  wt.  98 — the  sulphuric  acid  of  commerce — is  a  substance 
of  the  highest  importance,  its  manufacture  being  the  basis 
of  the  chemical  arts.  In  its  concentrated  form  it  is  known 
as  oil  of  vitriol,  and  is  a  colorless,  heavy  liquid,  of  an 
oily  consistency,  and  sharp,  sour  taste. 
•  It  is  manufactured  on  the  large  scale  by  mingling  sul 
phurous  acid  gas,  nitric  acid  gas,  and  steam,  in  large  lead- 
lined  chambers,  the  floors  of  which  are  covered  with  wa 
ter.  The  sulphurous  acid  takes  up  oxygen  from  the  nitric 
acid,  and  the  sulphuric  acid  thus  formed  dissolves  in  the 
water,  and  is  afterwards  boiled  down  to  the  proper  strength 
in  glass  vessels. 

The  chief  agricultural  application  of  commercial  ^sul 
phuric  acid  is  in  the  preparation  of  j  superphosphate)  of 
lime,"  which  is  consumed  as  a  fertilizeFTn~immense  quan- 
tities.  This  is  made  by  mixing  together  dilute  sulphuric 
acid  with  bone-dust,  bone-ash,  or  some  mineral  phosphate. 

Sulphuric  acid  occurs  in  the  free  sta^,HffioTTgh~F2rtreme- 
ly  dilute,  in  certain  natural  waters,  as  in  the  Oak  Orchard 
Acid  Spring  of  Orleans,  N.  Y.,  where  it  is1  produced  by 
the  oxidation  of  sulphide  of  iron. 

Sulphuric  acid  is  very  corrosive  and  destructive  to  most 
vegetable  and  animal  matters. 

EXP.  53.— Stir  a  little  oil  of  vitriol  with  a  pine  stick.  The  wood  is 
Immediate!}'  browned  or  blackened,  and  a  portion  of  it  dissolves  in  the 
acid,  communicating  a  dark  color  to  the  latter.  The  commercial  acid  is 
often  browu  from  contact  with  straws  and  chips. 

Strong  sulphuric  acid  produces  great  heat  when  mixed  with  water,  as 
is  done  for  making  superphosphate. 

EXP.  51. — Place  in  a  thin  glass  vessel,  as  a  beaker  glass,  30  c.  c.  of  wa 
ter;  into  this  pour  in  a  fine  stream  130  grams  of  oil  of  vitriol,  stirring 
all  the  while  with  a  narrow  test  tube,  containing  a  teaspoonful  of  water. 
If  the  acid  be  of  full  strength,  so  much  heat  is  thus  generated  as  to  boil 
the  water  in  the  stirring  tube. 

In  mixing  oil  of  vitriol  and  water,  the  acid  should  always  be  slowly 
poured  into  the  water,  with  stirring,  as  above  directed.  When  water  ia 
added  to  the  acid,  it  floats  upon  the  la*  ;er,  or  mixes  with  it  but  super 


THE    ASH    OF   PLANTS.  117 

flcially,  and  the  liquids  may  be  thrown  about  by  the  sudden  ijrmation 
of  steam  at  the  points  of  contact,  when  subsequently  stirred. 

Sulphuric  acid  forms  with  the  bases  an  important  class 
of  salts — the  sulphates — to  be  presently  noticed,  some  of 
which  exist  in  the  ash,  as  well  as  in  the  sap  of  plants. 
When  organic  matters  containing  sulphur,  as  hair,  album 
in,  etc.,  are  burned  with  full  access  of  air,  this  element  re 
mains  in  the  ash  as  sulphates,  or  is  partially  dissipated  as 
sulphurous  acid. 

PHOSPHOKFS     AND     ITS     COMPOUNDS. 

Phosphorus,  Sym.  P,  at.  wt.  31,  has  been  sufficiently 
described,  (p.  43.)  Of  its  numerous  compounds  but  two 
require  additional  notice. 

Anhydrous  Phosphoric  Acid,  Sym.  PQ  O6,  mo.  wt.  142, 
does  not  occur  as  such  in  nature.  When  phosphorus  is 
burned  in  dry  air  or  oxygen,  anhydrous  phosphoric  acid 
is  the  snow-like  product,  (Exp.  18.)  It  has  no  sensible 
acid  properties  until  it  has  united  to  water,  which  it  com 
bines  with  so  energetically  as  to  produce  a  hissing  noise 
from  the  heat  developed.  On  boiling  it  with  water  for 
some  time,  it  completely  dissolves,  and  the  solution  con 
tains — • 

Hydrated  Phosphoric  Acid,  Sym.  P2  O5,  3  H2  O,  196, 
or  H3  PO4,  98. — The  chief  interest  which  this  compound 
has  for  the  agriculturist  lies  in  the  fact  that  the  com 
binations  which  are  formed  between  it  and  various  bases 
—phosphates — are  among  the  most  important  ingredients 
of  plants  and  their  ashes. 

When  bodies  containing  phosphorus  in  other  forms  than 
phosphoric  acid,  as  protagon,  (p.  93,)  and,  perhaps,  some 
of  the  albuminoids,  are  disorganized  by  heat  or  decay  the 
phosphorus  appears  in  the  ashes  or  residue,  in  the  con 
dition  of  phosphoric  acid  or  phosphates. 

The  formation  of  several  phosphates  has  been  shown  in 


118  HOW   CROPS   GKOW. 

Exp.  20.     Further  account  of  them  will  be  given  undef 
the  metals. 

CHLORINE      AND      ITS     COMPOUNDS. 

Chlorine,  Sym.  Cl,  at.  wt.  35.5. — This  element  exists  in 
the  free  state  as  a  greenish-yellow,  suffocating  gas,  which 
has  a  peculiar  odor,  and  the  property  of  bleaching  vege 
table  colors.  It  is  endowed  with  the  most  vigorous 
affinities  for  many  other  elements,  and  hence  is  never  met 
with,  naturally,  in  the  free  state. 

Sprengel  claims  to  have  found  that  Olaux  maritirna  and  Snlicornla  her- 
baeea,  plants  growing  in  salt  marshes,  exhale  chlorine.  He  says  that  the 
chlorine  thus  evolved  is  very  quickly  converted  into  chlorhydric  acid, 
by  acting  on  the  vapor  of  water  which  exists  in  the  atmosphere.  Such 
an  exhalation  of  chlorine  is  manifestly  impossible.  The  gas,  were  it 
eliminated  within  the  plant,  would  be  consumed  before  it  could  escape 
into  the  atmosphere.  Chlorhydric  acid  is  evolved  from  the  mud  of  salt 
marshes  when  left  bare  by  ebb  of  the  tide,  and  exposed  to  the  heat  of 
the  summer  sun.  It  conies  from  the  mutual  decomposition  of  chloride 
of  magnesium  and  water, 

Mg  Cla  +  Ha  0  =  Mg  O  +  2  H  Cl. 

EXP.  55. — Chlorine  mtiy  be  prepared  by  heating  a  mixture  of  chlor- 
hydiic  acid  and  black  oxide  of  manganese  or  red-lead.  The  gas  being 
nearly  five  times  as  heavy  us  common  air,  may  be  collected  in  gl;iss  bot 
tles  by  passing  the  tube  which  delivers  it  to  the  bottom  of  the  receiving 
vessel.  Care  must  betaken  not  to  inhale  it,  as  it  energetically  attacks 
the  interior  of  the  breathing  passages,  producing  the  disagreeable 
symptoms  of  a  cold. 

Chlorine  dissolves  in  water,  forming  a  yellow  solution. 
Very  weak  chlorine  water  was  found  by  Humboldt  to  fa 
cilitate  the  sprouting  of  seeds. 

In  some  form  of  combination  chlorine  is  distributed  over 
the  whole  earth,  and  is  never  absent  from  the  plant. 

The  compounds  of  chlorine  are  termed  chlorides,  and 
may  be  prepared,  in  most  cases,  by  simply  putting  their 
elements  in  contact,  at  ordinary  or  slightly  elevated  tem 
peratures. 

Clilorliydric  acid,  also  Ifydrochloric  acid,  Sym.  H  Cl,  mo.  wt. 
3G.5. — When  Chlorine  :ind  Hydrogen  gases  are  mingled  together,  they 
slowly  combine  if  exposed  to  diffused  liti'ht;  but  if  placed  in  the  sun 
shine,  ihcy  tius.o  explosively,  and  chloride  of  hydrogen  or  e.hlorhydiie 


THE   ASH    OF   PLANTS.  119 

acid  is  formed.  This  compound  is  a  gas  that  dissolves  with  great  avidity 
in  water,  forming  a  liquid  which  has  a  sharp,  sour  taste,  and  possesses 
all  the  characters  of  an  acid. 

The  muriatic  acid  of  the  apothecary  is  water  holding  in  solution  several 
hundred  times  its  bulk  of  chlorhydric  acid  gas,  and  is  prepared  from  com 
mon  salt,  whence  its  ancient  name  spirits  of  salt. 

Chlorhydric  acid  is  the  usual  source  of  chlorine  gas.  The  latter  is 
evolvil  from  a  heated  mixture  of  this  acid  with  peroxide  of  manganese. 
In  tt  '.3  reaction  the  hydrogen  of  the  chlorhydric  acid  unites  with  the 
oxygen  of  the  peroxide  of  manganese,  producing  water,  while  chloride 
of  manganese  and  free  chlorine  are  separated. 

4  H  Cl  +  Mn  Oa  =  Mri  Cla  +  2  Ha  O  +  2  01. 

When  chlorine  dissolved  in  water,  is  exposed  to  the  sun-light,  there 
ensues  a  change  the  reverse  of  that  just  noticed.     Water  is  decomposed, 
its  oxygen  is  set  free,  and  chlorhydric  acid  is  formed, 
H2  O  +  2  Cl  =  2  H  Cl  +  O. 

This  reaction  probably  takes  place  when  the  germination  of  seeds  is 
hastened  by  chlorine.  The  oxygen  thus  liberated  is  doubtless  the  real 
agent  which  excites  growth  in  the  sleeping  germ. 

The  two  reactions  just  noticed  are  instructive  examples  of  the  differ 
ent  play  of  affinities  between  several  elements  under  unlike  circum 
stances. 

Chlorhydric  acid,  being  volatile,  does  not  occur  in  the  ashes  of  plants, 
nor  probably  in  the  plant  itself,  unless,  as  may  possibly  happen,  it  is 
formed  in,  and  exhales  from  the  vegetation,  as  it  sometimes  does  from 
the  mud  of  salt  marshes,  (p.  118.)  Chlorhydric  gas  is  found  in  volcanic 
emanations. 

This  acid  is  a  ready  means  of  converting  various  metals  or  metallic 
oxides  into  chlorides,  and  its  solution  in  water  is  a  valuable  solvent  and 
reagent  for  the  purposes  of  the  chemist. 

Iodine,  Sym.  I,  at.  wt.  127. — This  interesting  body  is  a  black  solid  at 
ordinary  temperatures,  having  an  odor  resembling  that  of  chlorine.  Gent 
ly  heated,  it  is  converted  into  a  violet  vapor.  It  occurs  in  sea-weeds, 
and  is  obtained  from  their  ashes.  It  gives  with  starch  a  blue  or  purple 
compound,  and  is  hence  employed  as  a  test  for  that  substance,  (p.  64.) 
It  is  analogous  to  chlorine  in  its  chemical  relations.  It  is  not  known  to 
occur  in  sensible  quantity  in  agricultural  plants,  although  it  may  -well 
exist  in  the  grasses  of  salt-bogs,  and  in  the  produce  of  soils  which  are 
manured  with  sea-weed. 

It romi  ii<>  and  Fluorine  may  also  exist  in  very  small  quantity  in 
plants,  but  these  elements  require  no  further  notice  in  this  treatise. 

SILICON     AND     ITS     COMPOUNDS. 

Silicon,  Sym.  Si,  at.  wt.  28. — This  element,  in  the  free 
state,  is  only  known  to  the  chemist.  Tt  may  be  prepared 


120  HOW   CKOPS    GROW. 

in  three  modifications :  one,  a  brown,  powdery  substance ; 
another,  resembling  black-lead,  (p.  31,)  and  a  third,  that 
occurs  in  crystals,  having  the  form  and  nearly  the  hard 
ness  of  the  diamond. 

Anhydrous  Silicic  Acid,  Sym.  Si  O2,  mo.  wt.  60.— This 
compound,  known  also  as  Silica,  and  anciently  termed 
Silex,  is  widely  diffused  in  nature,  and  occurs  to  an  enor 
mous  extent  in  rocks  and  soils,  both  in  the  free  state  and 
in  combination  with  other  bodies. 

Free  silica  exists  in  nearly  all  soils,  and  in  many  rocks, 
especially  in  sandstones  and  granites,  in  "the  form  known 
to  mineralogists  as  quartz.  The  glassy,  white  or  trans 
parent,  often  yellowish  or  red  fragments  of  common  sand, 
which  are  hard  enough  to  scratch  glass,  are  almost  inva 
riably  this  mineral.  In  the  purest  state,  it  is  rock-crystal. 
Jasper,  flint,  and  agate,  are  somewhat  less  pure  silica. 

Silicates. — Anhydrous  silicic  acid  is  extremely  insoluble 
in  pure  water  and  in  most  acids.  It  has,  therefore,  none 
of  the  sensible  qualities  of  acids,  but  is  nevertheless  ca 
pable  of  union  with  bases.  It  is  slowly  dissolved  by  strong, 
and  especially  by  hot  solutions  of  potash  and  soda,  form 
ing  soluble  silicates  of  these  alkalies. 

EXP.  56. — Formation  of  silicate  of  potash.  Heat  a  piece  of  quartz  or 
flint,  as  large  as  a  chestnut,  as  hot  as  possible  iu  the  fire,  and  quench 
suddenly  in  cold  water.  Reduce  it  to  fine  powder  in  a  porcelain  mortar, 
and  boil  it  in  a  porcelain  dish  with  twice  its  weight  of  caustic  potash, 
and  eight  or  ten  times  as  much  water,  for  two  hours,  taking  care  to  sup 
ply  the  water  as  it  evaporates.  Pour  off  the  whole  into  a  tall  narrow 
bottle,  and  leave  at  rest  until  the  undissolved  silica  has  settled.  The 
clear  liquid  is  a  basic  silicate  of  potash,  i.  e.  a  silicate  which  contains  a 
number  of  molecules  of  base  for  each  molecule  of  silica.  It  has,  in  fact, 
the  taste  and  feel  of  potash  solution.  The  so-called  water-glass,  now  em 
ployed  in  the  arts,  is  a  similar  silicate  of  potash  or  soda. 

When  silica  is  strongly  heated  with  potash  or  soda,  or 
with  lime,  magnesia,  or  oxide  of  iron,  it  readily  melts  to 
gether  and  unites  with  these  bodies,  though  nearly  infus 
ible  by  itself,  and  silicates  are  the  result.  The  silicates 
thus  formed  with  potash  and  soda  are  soluble  in  water,  like 


THE    ASH    OF    PLANTS. 

the  product  of  Lxp.  56,  when  the  alkali  exceeds  a  certain 
proportion — when  highly  basic ;  but  with  silica  in  excess, 
(acid  silicates,)  they  dissolve  with  difficulty.  A  jnixed 
silicate  of  alkali  and  lime,  alumina,  or  iron,  with  a  large 
proportion  of  silica,  is  nearly  or  altogether  insoluble,  not 
only  in  water,  but  in  most  acids — constitutes,  in  fact,  ordi 
nary  glass. 

A  multitude  of  silicates  exist  in  nature  as  rocks  and 
minerals.  Ordinary  clay,  common  slate,  soapstone,  mica, 
or  mineral  isinglass,  feldspar,  hornblende,  garnet,  and 
other  compounds  of  frequent  and  abundant  occurrence,  are 
silicates.  The  natural  silicates  are  of  two  classes,  viz.,  the 
acid  silicates,  (containing  a  preponderance  of  silica,)  and 
basic  silicates,  (with  large  proportion  of  base):  the  former 
are  but  slowly  dissolved  or  decomposed  by  acids,  while 
the  latter  are  readily  attacked  even  by  carbonic  acid. 
Many  native  silicates  are  anhydrous,  or  destitute  of  water ; 
others  are  hydrous,  i.  e.  they  contain  water  as  a  large  and 
essential  ingredient. 

Hydrated  Silica. — Various  compounds  of  silica  with 
water  are  known  to  the  chemist.  Of  these  but  three  need 
be  mentioned  here. 

Soluble  Silica. — This  body,  doubtless  a  hydrate,  is  known 
only  in  a  state  of  solution.  It  is  formed  when  the  solution 
of  an  alkali-silicate  is  decomposed  by  means  of  a  large  ex 
cess  of  some  strong  acid,  like  the  chlorhydric  or  sulphuric. 

EXP.  57. — Dilute  half  the  solution  of  silicate  of  potash  obtained  in 
Exp.  56  with  ten  times  its  volume  of  water,  and  add  diluted  chlorhydric 
acid  gradually  until  the  liquid  tastes  sour.  In  this  Exp.  the  chlorhydric 
acid  decomposes  and  destroys  the  silicate  of  potash,  uniting  itself  with 
the  base  with  production  of  chloride  of  potassium,  which  dissolves  in 
the  water  present.  The  silica  thus  liberated  unites  chemically  with  wa 
ter,  and  remains  also  in  solution. 

By  appropriate  methods  Doveri  and  Graham  have  re 
moved  from  solutions  like  that  of  the  last  Ex  p.  everything 
but  the  silica,  and  obtained  solutions  of  silica  in  pure  wa 
ter.     Graham  prepared  a  liquid  that  gave,  when  evaporat- 
6 


122  HOW   CROPS   GKOW. 

ed  and  seated,  14  per  cent  of  anhydrous  silica.  This  eo 
lution  was  clear,  colorless,  and  not  viscid.  It  reddened 
litmus  paper  like  an  acid.  Though  not  sour  to  the  taste, 
it  produced  a  peculiar  feeling  on  the  tongue.  Evaporated 
to  dryness  at  a  low  temperature,  it  left  a  transparent, 
glassy  mass,  which  had  the  composition  Si  OQ,  H2O.  This 
dry  residue  was  insoluble  in  water.  These  solutions  of  silica 
in  pure  water  are  incapable  of  existing  for  a  long  tune 
without,  suffering  a  remarkable  change.  Even  when  pro 
tected  from  all  external  agencies,  they  sooner  or  later,  usu 
ally  in  a  few  days  or  weeks,  lose  their  fluidity  and  trans 
parency,  and  coagulate  to  a  stiff  jelly,  from  the  separatioji 
of  a  nearly  insoluble  hydrate  of  silica,  which  we  shall  des 
ignate  as  gelatinous  silica. 

The  addition  of  Toloo  of  an  alkali  or  earthy  carbonate, 
or  of  a  lew  bubbles  of  carbonic  acid  gas  to  the  strong  so 
lutions,  occasions  their  immediate  gelatinization.  A  mi 
nute  quantity  of  potash  or  soda,  or  excess  of  chlorhydric 
acid,  prevents  their  coagulation. 

Gelatinous  Silica. — This  substance,  M  hich  results  from 
the  coagulation  of  the  soluble  silica  just  described,  usually 
appears  also  when  the  strong  solution  of  a  silicate  has 
strong  chlorhydric  acid  added  to  it,  or  when  a  silicate  is 
decomposed  by  direct  treatment  with  a  concentrated  acid. 

It  is  a  white,  opaline,  or  transparent  jelly,  which,  on  dry 
ing  in  the  air,  becomes  a  fine,  white  powder,  or  forms 
transparent  grains.  This  powder,  if  dried  at  ordinary 
temperatures,  is  3  Si  O2,  2  H2O.  At  the  temperature  of 
212°  F.,  it  loses  half  its  water.  At  a  red  heat  it  becomes 
anhydrous. 

Gelatinous  silica  is  distinctly,  though  very  slightly,  sol 
uolc  in  water.  Fuchs  and  Bresser  have  found  by  experi 
ment  that  100,000  parts  of  water  dissolve  13  to  14  parts 
of  gelatinous  silica. 

The  hydrates  of  silica  which  have  been  subjected  to  a 


THE    ASH    OF   PLANTS.  123 

heat  of  212°  or  more,  appear  to  be  totally  insoluble  in  p*  j*e 
water.' 

All  the  hydrates  of  silica  are  readily  soluble  in  solutions 
of  the  alkalies  and  alkali  carbonates,  and  readily  unite 
with  moist,  slaked  lime,  forming  silicates. 

EXP.  58. — Gelatinous  Silica.—  Pour  a  small  portion  of  the  solution  of 
silicate  of  potash  of  Exp.  56,  into  strong  chlorhydric  acid.  Gelatinous 
silica  separates  and  falls  to  the  bottom,  or  the  whole  liquid  becomes  a 
trau^arent  jelly. 

EXP.  59. — Conversion  of  soluble  into  insoluble  hydrated  silfca. — Evaporate 
the  solution  of  silica  of  Exp.  57,  which  contains  free  chlorhydric  acid, 
in  a  porcelain  dish.  As  it  becomes  concentrated,  it  is  very  likely  to  ge 
latinize,  as  happened  in  Exp.  58,  on  account  of  the  removal  of  the  sol 
vent.  Evaporate  to  perfect  dryness,  finally  on  a  water-batli  (i.  e.  on  a 
vessel  of  boiling  water  which  is  covered  by  the  dish  containing  the  solu 
tion).  Add  to  the  residue  water,  which  dissolves  away  the  chloride  of 
potassium,  and  leaves  insoluble  hydrated  silica,  3  Si  02,  H2O,  as  a  gritty 
powder. 

In  the  ash  of  plants,  silica  is  usually  found  in  combination 
with  alkalies  or  lime,  owing  to  the  high  temperature  to 
which  it  has  been  subjected. 

In  the  plant,  however,  it  exists  chiefly,  if  not  entirely, 
in  the  free  state. 

Titanium,  an  element  which  has  many  analogies  with  silicon, 
though  rarely  occurring  in  large  quantities,  is  yet  often  present  in  the 
form  of  Titanic  acid,  Ti  O2,  in  rocks  and  soils,  and  according  to  Salm 
Horstmar  may  exist  in  the  ashes  of  barley  and  oats.  • 

Arsenic,  in  minute  quantity,  has  been  found  by  Davy  in  turnips 
which  had  been  manured  with  a  fertilizer  (superphosphate),  in  whose 
preparation,  oil  of  vitriol,  containing  this  substance,  was  employed. 

The  metallic  elements  which  remain  to  be  noticed,  viz. : 
Potassium,  Sodium,  Calcium,  Magnesium,  Iron,  Manga 
nese,  (Lithium,  Rubidium,  Caesium,  Aluminum,  Zinc,, 
and  Copper,)  are  basic  in  their  character,  i.  e.,  they  unite 
with  the  acid  bodies  that  have  just  been  described  to 
produce  salts.  Each  one  is,  in  this  sense,  the  base  of  a 
series  of  saline  compounds. 

ALKALI-METALS. — The  elements  Potassium,  Sodium, 
(Lithium,  Rubidium,  and  Caesium)  are  termed  alkali- 


124  HOW   CBOPS   GROW. 

metals.  Their  oxides  are  very  soluble  in  water,  and  are 
called  alkalies.  The  metals  themselves  do  not  occur  in 
nature,  and  can  only  be  prepared  by  tedious  chemical 
processes.  They  are  silvery-white  bodies,  and  are  lighter 
than  water.  Exposed  to  the  air,  they  quickly  tarnish  from 
the  absorption  of  oxygen,  and  are  rapidly  converted  into 
the  corresponding  alkalies.  Thrown  upon  water,  they 
mostly  inflame  and  burn  with  great  violence,  decomposing 
the  liquid,  Exp.  11. 

Of  the  alkali-metals,  Potassium  is  invariably  found  in 
all  plants.  Sodium  is  especially  abundant  in  marine  and 
strand  vegetation ;  it  is  generally  found  in  agricultural 
plants,  but  is  occasionally  absent  from  them. 

POTASSIUM     AND     ITS      COMPOUNDS. 

Potassium,  sym.  K  ;*  at.  wt.  39. — When  heated  in  the 
air,  this  metal  burns  with  a  beautiful  violet  light,  and 
forms  potash. 

Potash,  K2O,  94,  is  the  alkali,  and  base  of  the  potash- 
salts. 

Hydrate  of  Potash,  KaO,  H2O,  112,  or  K  H  0, 56,  is  the 
caustic  potash  of  the  apothecary  and  chemist.  It  may  be 
procured  in  white,  opaque  masses  or  sticks,  which  rapidly 
absorb  moisture  and  carbonic  acid  from  the  air,  and 
readily  dissolve  in  water,  forming  potash-lye.  It  strongly 
corrodes  many  vegetable  and  most  animal  matters,  and 
dissolves  fats,  forming  potash-soaps.  It  unites  with  acids 
like  KaO,  water  being  set  free. 

SODIUM     AND     ITS      COMPOUNDS. 

Sodium,  Na,f  23. — Burns  with  a  brilliant,  orange-yellow 
flame. 

*  From  the  Latin  name  Kailum, 

*  From  the  Latin  name  Natrium. 


THE   ASH    OF  PLANTS.  126 

Soda,  Na2O,  62. — This  alkali,  the  base  of  the  soda  salts, 
is  not  distinguishable,  from  potash  by  its  sensible  proper 
ties. 

Hydrate  of  Soda,  or  Caustic  Soda,  1STaaO,  IT2O,  80,  or 
Na  H  O,  40. — This  body  is  like  caustic  potash  in  appear 
ance  and  general  characters.  It  forms  soaps  with  the 
various  fats.  While  the  potash-soaps  are  usually  soft, 
those  made  with  soda  are  commonly  hard. 

LITHIUM  :  RUBIDIUM  :  CAESIUM. 

Lithium,  Li,  7.— The  compounds  of  this  metal  are  of  much  rarer 
occurrence  than  those  of  Potassium  and  Sodium.  The  element  itself  is 
the  lightest  metal  known,  being  but  little  more  than  half  as  heavy  as 
water.  It  burns  with  a  vivid  white  light  when  heated  in  the  air. 

I^ithiii,  Li20,  30,  and  its  Hydrate,  closely  resemble  the  correspond 
ing  compounds  of  the  two  elements  above  described.  They  yield  by 
union  with  acids  the  lithia-salts. 

Rubidium,  Kb,  85.5,  and  Caesium,  Cs,  133.— Besides  Potas 
sium,  Sodium,  and  Lithium,  there  are  two  other  recently  discovered 
alkali-metals,  viz. :  Rubidium  and  Caesium.  These  elements  are  com 
paratively  rare,  although  they  appear  to  be  widely  distributed  in  nature 
in  minute  quantity. 

Rubidium  has  been  found  in  the  ashes  of  tobacco  and  sugar-beet,  as 
well  as  in  commercial  potash.  Caesium,  which  is  the  rarer  of  the  two, 
has  as  yet  not  been  detected  in  the  ashes  of  plants,  but  undoubtedly  oc 
curs  in  them.  These  metals  and  their  compounds  have,  in  general,  the 
closest  similarity  to  the  other  alkali-metals. 

ALKALI-EARTH  METALS.  —  The  two  metallic  elements 
next  to  be  noticed,  viz. :  Calcium  and  Magnesium,  give, 
with  oxygen,  the  alkali-earths,  lime  and  magnesia.  The 
metals  are  only  procurable  by  difficult  chemical  processes, 
and  from  their  eminent  oxidability  are  not  found  in  nature. 
They  are  but  a  little  heavier  than  water.  Their  oxides  are 
but  slightly  soluble  in  water. 

CALCIUM     AND     ITS     COMPOUNDS. 

Calcium,  Ca,  40,  is  a  brilliant  ductile  metal  having  a 
light  yellow  color.  In  moist  air  it  rapidly  tarnishes  and 
acquires  a  coating  of  lime 


126  HOW   CROPS   GROW. 

Lime,  CaO,  56. — Is  the  result  of  the  oxidation  of  cal 
cium.  It  is  prepared  for  use  in  the  arts  by  subjecting 
limestone  or  oyster-shells  to  an  intense  heat,  and  usually 
retains  the  form  and  much  of  the  hardness  of  the  material 
from  which  it  is  made.  It  has  the  bitter  taste  and  corrod 
ing  properties  of  the  alkalies,  though  in  a  less  degree.  It 
is  often  called  quick-lime,  to  distinguish  it  from  its  com 
pound  with  water.  It  may  occur  in  the  ashes'  of  plants 
when  they  have  been  maintained  at  a  high  heat  after  the 
volatile  matter  has  been  burned  away.  It  is  the  base  of 
<;he  salts  of  lime. 

Hydrate  of  Lime,  CaO,  HaO,  or  CaH2  O2,  74.— Quick 
lime,  when  exposed  to  the  air,  gradually  absorbs  water 
and  falls  to  a  fine  powder.  It  is  then  said  to  be  air-slaked. 
When  water  is  poured  upon  quick-lime  it  penetrates  the 
pores  of  the  latter,  and  shortly  the  falling  to  powder  of 
the  lime  and  the  development  of  much  heat,  give  evi 
dence  of  chemical  union  between  the  lime  and  the  water. 
This  chemical  combination  is  further  proved  by  the  in 
crease  of  weight  of  the  lime,  56  Ibs.  of  quick-lime  becom 
ing  74  Ibs.  by  water-slaking.  On  heating  slaked  lime  to 
redness,  its  water  may  be  expelled. 

When  lime  is  agitated  for  some  time  with  muclt  water, 
and  the  mixture  is  allowed  to  settle,  the  clear  liquid  is 
found  to  contain  a  small  amount  of  lime  in  solution  (one 
part  of  lime  to  700  parts  of  water).  This  liquid  is  called 
lime-water,  and  has  already  been  noticed  as  a  test  for  car 
bonic  acid.  Lime-water  has  the  alkaline  taste  in  a  marked 


degree. 


MAGNESIUM     AND     ITS     COMPOUNDS. 


Magnesium,  Mg,  24 — Metallic  magnesium  has  a  silver- 
white  color.  When  heated  in  the  air  it  burns  with  ex 
treme  brilliancy  (magnesium  light),  and  is  converted  into 
magnesia. 


THE    ASH    OF   PLANTS.  127 

Magnesia,  Mg  O,  40,  is  the  oxide  of  magnesium.  It  is 
found  in  the  drug-stores  in  the  shape  of  a  bulky  white 
powder,  under  the  name  of  calcined  magnesia.  It  is  pre 
pared  by  subjecting  either  hydrate,  carbonate,  or  nitrate, 
of  mao-nesia  to  a  strong  heat.  It  occurs  in  the  ashes  of 

£3  O 

plants. 

Hydrate  of  Magnesia,  Mg  O  II2O,  is  produced  slowly 
and  without  heat,  when  magnesia  is  mixed  with  water.  It 
occurs  as  a  transparent,  glassy  mineral  (Brucite)  at  Texas, 
Penn.,  and  a  few  other  places.  It  readily  absorbs  carbonic 
acid,  and  passes  into  carbonate  of  magnesia.  Hydrate  of 
magnesia  is  so  slightly  soluble  in  water  as  to  be  tasteless 
/t  requires  55,000  times  its  weight  of  water  for  solution, 
(Fresenius). 

HEAVY  METALS. — The  two  metals  remaining  to  notice 
are  Iron  and  Manganese.  These  again  considerably  re 
semble  each  other,  though  they  differ  exceedingly  from 
the  metals  of  the  alkalies  and  alkali-earths.  They  are 
about  eight  times  heavier  than  water.  Each  of  these 
metals  forms  two  basic  oxides,  which  are  totally  insoluble 
in  pure  water. 

IKON     AND     ITS     COMPOUNDS. 

Iron,  Fe,*  56. — The  properties  of  metallic  iron  are  so 
well  known  that  we  need  not  occupy  any  space  in  reca 
pitulating  them. 

Protoxide  f  Of  Iron,  Fe  O,  72. — When  sulphuric  acid 
in  a  diluted  state  is  -put  in  contact  with  metallic  iron,  hy 
drogen  gas  shortly  begins  to  escape  in  bubbles  from  the 
liquid,  and  the  iron  dissolves,  uniting  with  the  acid  to  form 
the  protosulphate  f  of  iron,  the  salt  known  commonly  as 
copperas  or  green- vitriol. 

*  From  the  Latin  name  Ferrum. 

t  The  prefix  prot  or  proto,  from  the  Greek,  meaning  jZp^,  is  employed  to  dis 
tinguish  this  oxide  and  its  salts  from  the  compounds  to  te  subsequently  da- 
scribed 


128  HOW   CROPS   GROW 

H30,  S03,  +  Fe  =  Fe  O,  S03  +  H,.  , 
If,  now,  lime-water  or  potash-lye  be  added  to  the 
tion  of  iron  thus  obtained,  a  white  or  greenish-white  pre 
cipitate  separates,  which  is  a  hydrated  protoxide  of  iron, 
(Fe  O,2  H2O).  This  precipitate  rapidly  absorbs  oxygen 
from  the  air,  becoming  black  and  finally  brown.  The 
anhydrous  protoxide  of  iron  is  black.  Carbonate  of 
protoxide  of  iron  is  of  frequent  occurrence  as  a  mineral 
(spathic  iron),  and  exists  dissolved  in  many  mineral  wa 
ters,  especially  in  the  so-called  chalybeates. 

Sesquioxide  Of  Iron,*  Fe2  O3,  160.— When  protoxide 
of  iron  is  exposed  to  the  air,  it  acquires  a  brown  color  from 
union  with  more  oxygen,  and  becomes  hydrated  sesqui- 
oxide.  The  yellow  or  brown  rust  which  forms  on  surfaces 
of  metallic  iron  when  exposed  to  moist  air  is  the  same 
body.  Iron  in  the  form  of  sesquioxide  is  found  in  the  ashes 
of  all  agricultural  plants,  the  other  oxides  of  iron  passing 
into  this  when  exposed  to  air  at  high  temperatures.  It  is 
found  in  immense  beds  in  the  earth,  and  is  an  important 
ore,  (specular  iron,  hematite).  It  dissolves  in  acids, 
forming  sesquisdlts  of  iron,  which  have  a  yellow  color. 

MAGNETIC  OXIDE  OP  IRON,  Fes  O4,  or  FeO,  Fea  03,  is  a  combination 
of  the  two  oxides  above  mentioned.  It  is  black,  and  is  strongly  attract 
ed  by  the  magnet.  It  constitutes,  in  fact,  the  native  magnet,  or  load 
stone,  and  is  a  valuable  ore  of  iron. 

MANGANESE      AND     ITS      COMPOUNDS. 

Manganese,  Mn,  55. — Metallic  manganese  is  difficult  to 
procure  in  the  free  state,  and  much  resembles  iron.  Ita 
oxides  which  concern  the  agriculturist  are  analogous  to 
those  of  iron  just  noticed. 

Protoxide  Of  Manganese,  Mn  O,  71,  has  an  olive- 
green  color.  It  is  the  base  of  all  the  usually  occurring 

*  The  prcflx  sesqui  (one,  and  a  half)  is  applied  to  tl  ose  oiides  in  which  the 
ratio  of  metal  to  oxygen  is  as  one  to  one  and  a  half,  or,  what  is  the  sacie,  at 
two  to  three.  The  above  compound  is  also  called  peroxide  of  iron. 


THE   ASH    OF   PLANTS.  129 

§alts  of  manganese.  Its  hydrate,  prepared  by  decompos 
ing  protosulphate  of  manganese  by  lime-water,  is  a  white 
substance,  which,  on  exposure  to  the  air,  shortly  becomes 
brown  and  finally  black  from  absorption  of  oxygen.  The 
salts  of  protoxide  of  manganese  are  mostly  pale  rose-red 
in  color. 

Sesqnioxide  of"  Manganese,  Mna  03,  occurs  native  as  the 
mineral  braunite,  or,  combined  with  water,  as  manganite.  It  is  a  sub 
stance  having  a  red  or  black-brown  color.  It  dissolves  in  cold  acids, 
forming  salts  of  an  intensely  red  color.  These  are,  however,  easily  de 
composed  by  heat,  or  by  organic  bodies,  into  oxygen  and  protosalts. 

Red  Oxide  ol"  Manganese,  Mn3  04,  or  Mn  O,  Mn3  03.— This 
oxide  remains  when  manganese  or  any  of  its  other  oxides  are  subjected 
to  a  high  temperature  with  access  of  air.  The  metal  and  the  protoxide 
gain  oxygen  by  this  treatment,  the  higher  oxides  lose  oxygen  until  this 
compound  oxide  is  formed,  which,  as  its  symbol  shows,  corresponds  to 
the  magnetic  oxide  of  iron.  It  is  found  in  the  ashes  of  plants. 

Black  Oxide  of"  Manganese,  Mn  02.— This  body  is  found 
extensively  in  nature.  It  is  employed  in  the  preparation  of  oxygen  and 
chlorine,-  (bleaching  powder),  and  is  an  article  of  commerce. 

Some  other  metals  occur  as  oxides  or  salts  in  ashes,  though  not  in 
such  quantity  or  in  such  plants  as  to  possess  any  agricultural  significance 
in  this  respect. 

Alumina,  the  sesquioxide  of  the  metal  ALUMINUM,  is  found  in  con 
siderable  quantity  (20  to  50  per  cent)  in  the  ashes  of  the  ground  pine 
(Lycopodium).  It  is  united  with  an  organic  acid  (tartaric,  according  to 
Berzelius ;  malic,  according  to  Ritthausen)  in  the  plant  itself.  It  is  often 
found  in  small  quantity  in  the  ashes  of  agricultural  plants,  but  whether 
an  ingredient  of  the  plant  or  due  to  particles  of  adhering  clay  is  not  in 
all  cases  clear. 

Zinc  has  been  found  in  a  variety  of  yellow  violet  that  grows  in  th( 
zinc  mines  of  Aix  la  Chapelle. 

Copper  is  frequently  present  in  minute  quantity  in  the  ash  of  trees, 
especially  of  such  as  grow  in  the  vicinity  of  manufacturing  establish 
ments,  where  dilute  solutions  containing  copper  are  thrown  to  waste. 

The  salts  or  compounds  of  metals  with  non-metals 

found  in  the  ashes  of  plants  or  in  the  unburned  plant  re 
main  to  be  considered. 

Of  the  elements,  acids,  and  oxides,  that  have  been  no 
ticed  as  constituting  the  ash  of  plants,  it  must  be  remark 
ed  that  with  the  exception  of  silica,  magnesia,  oxide  of 
6* 


130  HOW   CROPS   GROW. 

iron,  and  oxide  of  manganese,  they  all  exist  in  the  ash  in 
the  form  of  salts,  (compounds  of  acids  and  bases).  In  the 
living  agricultural  plant  it  is  probable,  that  of  them  all, 
only  silica  occurs  in  the  uncombined  state. 

We  shall  notice  in  the  first  place  the  salts  which  may 
occur  in  the  ash  of  plants,  and  shall  consider  them  under 
the  following  heads,  viz. :  Carbonates,  Sulphates,  Phos 
phates,  and  Chlorides.  As  to  the  Silicates,  it  is  unneces 
sary  to  add  anything  here  to  what  has  been  already  men 
tioned. 

TIIE  CARBONATES  which  occur  in  the  ashes  of  plants 
are  those  of  Potash,  Soda,  and  Lime.  (Carbonate  of 
Rubidia,  similar  to  carbonate  of  soda,  and  Carbonate  of 
Lithia,  rather  insoluble  in  water,  may  also  be  present,  but 
in  exceedingly  minute  quantity.)  The  Carbonates  of  Mag 
nesia,  Iron,  and  Manganese,  are  decomposed  by  the  heat 
at  which  ashes  are  prepared. 

Carbonate  of  Potash,  K2O  CO2,  114.— The  pearl-ash 
of  commerce  is  a  tolerably  pure  form  of  this  salt.  When 
wood  is  burned,  the  potash  which  it  contains  is  found  in 
the  ash,  chiefly  as  carbonate.  If  wood-ashes  are  repeat 
edly  washed  or  leached  with  water,  all  the  salts  soluble  in 
this  liquid  are  removed  ;  by  boiling  this  solution  down  to 
dryness,  which  is  done  in  large  iron  pots,  crude  potash  is 
obtained,  as  a  dark  or  brown  mass.  This,  when  somewhat 
purified,  yields  pearl-ash.  Carbonate  of  potash,  when  pure, 
is  white,  has  a  bitter,  biting  taste — the  so-called  alkaline 
taste.  It  has  such  attraction  for  water,  that,  when  expos 
ed  to  the  air,  it  absorbs  moisture  and  becomes  a  liquid. 

If  chlorhydric  acid  be  poured  upon  carbonate  of  potash 
a  brisk  effervescence  immediately  takes  place,  owing  to  the 
escape  of  carbonic  acid  gas,  and  chloride  of  potassium  and 
water  are  formed  which  re-main  behind. 

K2O  CO3  +  2H  Cl  =  2K  Cl  +  HaO  +  CO2. 

Bicarbonate  of   Potash,  KHO  CO,.— A  solution  of 


THE   ASH    OF   PLANTS.  131 

carbonate  of  potash  when  exposed  to  carbonic  acid  gas 
absorbs  the  latter,  and  the  bicarbonate  of  potash  is  pro 
duced,  so  called  because  to  a  given  amount  of  potassium 
it  contains  twice  as  much  carbonic  acid  as  the  carbonate. 
P otash-salceratus  consists  essentially  of  this  salt.  It 
probably  exists  in  the  juices  of  various  plants. 

Carbonate  Of  Soda,  Na2O  CO2, 106. — This  substance,  so 
important  in  the  arts,  was  formerly  made  from  the  ashes 
of  certain  marine  plants  (Salsola  and  Salicomia),  in  a  man 
ner  similar  to  that  now  employed  in  wooded  countries  for 
the  preparation  of  potash.  It  is  at  present  almost  wholly 
obtained  from  common  salt  by  a  somewhat  complicated 
process.  It  occurs  in  commerce  in  an  impure  state  under 
the  name  of  Soda-ash.  When  nearly  pure  it  forms  sal- 
soda,  which  usually  exists  in  transparent  crystals  or  crys 
tallized  masses.  These  contain  63  per  cent  of  water,  which 
slowly  escapes  when  the  salt  is  exposed  to  the  air,  leaving 
the  anhydrous  (water-free)  carbonate  as  a  white,  opaque 
powder. 

Carbonate  of  soda  has  a  nauseous  alkaline  taste,  not 
nearly  so  decided,  however,  as  that  of  the  carbonate  of 
potash.  It  is  often  present  in  the  ashes  of  plants. 

Bicarbonate  of  Soda,  -NallO  CO2. — The  supercarbon- 
ate  of  soda  of  the  apothecary  is  this  salt  in  a  nearly  pure 
state.  The  soda-salcemtus  of  commerce  is  a  mixture  of 
this  with  some  simple  carbonate.  It  is  prepared  in  the 
same  way  as  the  bicarbonate  of  potash.  The  bicarbonates. 
both  of  potash  and  soda,  give  off  half  their  carbonic  acid 
at  a  moderate  heat,  and  lose  all  of  this  ingredient  by  con 
tact  with  excess  of  any  acid.  Their  use  in  baking  depends 
upon  these  facts.  They  neutralize  any  acid  (lactic  or 
acetic)  that  is  formed  during  the  "  rising  "  of  the  dough, 
and  assist  to  make  the  bread  "  light "  by  inflating  it  with 
jarbonic  acid  gas. 

Carbonate  of  Lime,  CaO  CO,,  112.— This  compound  is 


132  HOW   CROPS    GROW. 

the  white  powder  formed  by  the  contact  of  carbonic  acid 
with  lime-water.  When  hydrate  of  lime  is  exposed  to  the 
air,  the  water  it  contains  is  gradually  displaced  by  car 
bonic  acid>  and  carbonate  of  lime  is  the  result.  Air- 
slaked  lime  always  contains  much  carbonate.  This  salt 
is  distinguished  from  hydrate  of  lime  by  its  being  destitute 
of  any  alkaline  taste. 

In  nature  carbonate  of  lime  exists  to  an  immense  extent 
as  coral,  chalk,  marble,  and  limestone.  These  rocks,  when 
strongly  heated,  especially  in  a  current  of  air,  part  with 
their  carbonic  acid,  and  quick-lime  remains  behind. 

Carbonate  of  lime  occurs  largely  in  the  ashes  of  most 
plants,  particularly  of  trees.  In  the  manufacture  of  pot 
ash,  it  remains  undissolved,  and  constitutes  a  chief  part 
of  the  residual  leached  ashes. 

The  carbonate  of  lime  found  in  the  ashes  of  plants  is 
supposed  to  come  mainly  from  the  decomposition  by  heat 
of  organic  salts  of  lime,  (oxalate,  tartrate,  malate,  etc.,) 
which  exist  in  the  juices  of  the  vegetable,  or  are  abun 
dantly  deposited  in  its  tissues  in  the  solid  form.  Carbonate 
of  lime  itself  is,  however,  not  an  unusual  component  of 
vegetation,  being  found  in  the  form  of  minute,  rhombic 
crystals,  in  the  cells  of  a  multitude  of  plants. 

THE  SULPHATES  which  we  shall  notice  at  length  are 
those  of  Potash,  Soda,  and  Lime.  Sulphate  of  Magnesia 
is  well  known  as  epsom  salts,  and  Sulphate  of  Iron  is 
copperas  or  green- vitriol.  (Sulphate  of  Lithia  is  very 
similar  to  sulphate  of  potash.) 

Sulphate  of  Potash,  KaO  SO3,  174.— This  salt  may  be 
procured  by  dissolving  potash  or  carbonate  of  potash  in 
diluted  sulphuric  acid.  On  evaporating  its  solution,  it  is 
obtained  in  the  form  of  hard,  brilliant  crystals,  or  as  a 
white  powder.  It  has  a  bitter  taste.  Ordinary  potash, 
or  pearl-ash,  contains  several  per  cent  of  this  salt. 

Sulphate  of  Soda,  NaaO  So,,  U2.  —  Glauber's  salt  i§ 


%*( 

THE   ASH    OP   PLANTS.  133 

the  common  name  of  this  familiar  substance.  It  has  a 
bitter  taste,  and  is  much  employed  as  a  purgative  for  cat 
tle  and  horses.  It  exists,  either  crystallized  and  transpar 
ent,  containing  10  molecules,  or  nearly  56  per  cent,  of 
water,  or  anhydrous.  The  crystals  rapidly  lose  their  water 
when  exposed  to  the  air,  and  yield  the  anhydrous  salt  as  a 
white  powder. 

Sulphate  of  Lime,  CaO  SO3,  136.— The  burned  Plaster 
of  Paris  of  commerce  is  this  salt  in  a  more  or  less  pure 
state.  It  is  readily  formed  by  pouring  diluted  sulphuric 
acid  on  lime  or  marble.  It  is  found  in  the  ash  of  most 
plants,  especially  in  that  of  clover,  the  bean,  and  other 
legumes. 

In  nature,  sulphate  of  lime  is  usually  combined  with 
two  molecules  of  water,  and  thus  constitutes  G-ypsum, 
CaO  SO3  2H2O,  which  is  a  rock  of  frequent  and  extensive 
occurrence.  In  the  cells  of  many  plants,  as  for  instance 
the. bean,  gypsum  may  be  discovered  by  the  microscope 
in  the  shape  of  minute  crystals.  It  requires  400  times  its 
weight  of  water  to  dissolve  it,  and  being  almost  univer 
sally  distributed  in  the  soil,  is  rarely  absent  from  the  water 
of  wells  and  springs. 

THE  PHOSPHATES  which  require  special  description  are 
those  of  Potash,  Soda,  and  Lime. 

There  exist,  or  may  be  prepared  artificially,  numerous 
phosphates  of  each  of  these  bases.  The  chemist  is  ac 
quainted  with  no  less  than  thirteen  diiferent  phosphates  of 
soda.  But  three  classes  of  phosphates  have  any  immedi 
ate  interest  to  the  agriculturist.  As  has  been  stated  (p. 
117),  hydrated  phosphoric  acid  prepared  by  boiling  anhy 
drous  phosphoric  acid  with  water,  is  represented  by  the 
symbol  3H2O,  P2O6.  The  phosphates  may  be  regarded  as 
hydrated  phosphoric  acid  in  which  one,  two,  or  all  the 
molecules  of  water  are  substituted  by  the  same  number 
of  molecules  of  one  or  of  several  bases.  We  may  ill  us- 


134  HOW   CROPS   GROW. 

tr.-ite  this  statement  with  the  three  phosphates  of  lime, 
giving  in  one  view  their  mode  of  derivation,  their  sym 
bols,  and  the  names  which  we  shall  employ  in  this  treatise. 

a.— 3  H2O,  P2OB  and  CaO  give  HaO  and  2  H2O,  CuO, 
PQO6,  the  monocalcic*  phosphate  or  acid-phosphate  of 
lime. 

b.— 3  H2O,  P2O6  and  2  CaO  give  2  H3O  and  H2O,  2  Ca 
O  P2O6,  the  dicalcic  *  phosphate  or  neutral  phosphate  of 
lime. 

c.— 3  H2O,  P2O5  and  3  CaO  give  3  H2O  and  3  CaO  Pa 
OB,  the  tricalcic  *  phosphate  or  basic-phosphate  of  lime. 

Phosphates  Of  Potash. — Of  these  salts,  the  neutral  and 
subphosphates  exist  largely  (to  the  extent  of  40  to  50  per 
cent)  in  the  ash  of  the  kernels  of  wheat,  rye,  maize,  and 
other  bread  grains.  None  of  these  phosphates  occur  in 
commerce ;  they  closely  resemble  the  corresponding  soda- 
salts  in  their  external  characters. 

Phosphates  Of  Soda, — Of  these  the  disodic,  or  neutral 
phosphate,  2  Na2O,  H2O,  P2O6  +  12  Aqf,  alone  needs  no 
tice.  It  is  found  in  the  drug-stores  in  the  form  of  glassy 
crystals,  which  contain  12  molecules  (56  per  cent)  of  water. 
The  crystals  become  opaque  if  exposed  to  the  air,  from  the 
loss  of  water.  This  salt  has  a  cooling,  saline  taste,  and  is 
very  soluble  in  water. 

Phosphates  Of  Lime, — Both  the  neutral  and  subphos- 
phate  of  lime  probably  occur  in  plants.  The  neutral  or 
-ticalcic  salt,  (2  CaO  H2O,  P2O6  -f-  2  Aq),  is  a  white  crys 
talline  powder,  nearly  insoluble  in  water,  but  easily  soluble 
in  acids.  In  nature  it  is  found  as  a  urinary  concretion  in 

*  These  names  indicate  the  proportions  of  acid  and  base  in  the  compounds, 
•nd  may  be  translated  into  common  English,  thus :  One-lime  phosphate,  two-linu 
phosphate,  and  three -lime  phosphate  respectively. 

t  The  water  which  is  found  in  crystallized  salts  and  which  usually  may  be  ex 
pelled  at  a  gentle  heat,  is  termed  water  of  crystallization,  and  is  often  designated 
by  Aq.,  (from  the  Latin  Aqua),  to  distinguish  it  from  basic  water,  which  is  morv 
Intimately  combined. 


THE    ASH    OF   PLANTS.  135 

the  sturgeon  of  the  Caspian  Sea.  It  is  also  an  ingredient 
of  guanos,  and  probably  of  animal  excrements  in  general. 
The  tricalcic  phosphate,  or,  as  it  is  sometimes  termed, 
the  bone-phosphate,  3  CaO,  P2O6,  is  a  chief  ingredient  of 
the  bones  of  animals,  and  constitutes  90  to  95  per  cent  of 
the  ash  or  earth  of  bones.  It  may  be  formed  by  adding  a 
solution  of  lime  to  one  of  phosphate  of  soda,  and  appears 
as  a  white  precipitate.  It  is  insoluble  in  pure  water,  but 
dissolves  in  acids  and  in  solutions  of  many  salts.  In  the 
mineral  kingdom  tricalcic  phosphate  is  the  chief  ingredient 
of  apatite  and  phosphorite.  These  minerals  are  employed 
in  the  preparation  of  the  so-called  superphosphate  of  lime, 
which  is  consumed  to  an  enormous  extent  as  a  turnip-fer 
tilizer.  The  superphosphate  of  commerce,  when  genuine, 
is  essentially  a  mixture  of  sulphate  of  lime  with  the  three 
phosphates  above  noticed,  of  which  the  monocalcic  phos 
phate  should  predominate. 

The  Phosphates  of  Magnesia,  Iron,  and  Manganese, 

are  bodies  insoluble  in  water,  and  require  no  particular 
notice. 

THE  CHLORIDES  are  all  characterized  by  their  ready  solu 
bility  in  water.  The  chlorides  of  Lithium,  Calcium,  and 
Magnesium,  are  deliquescent,  i.  e.,  they  liquefy  by  absorb 
ing  moisture  from  the  air.  The  chlorides  of  Potassium 
and  Sodium  alone  need  to  be  described. 

Chloride  Of  Potassium,  K  Cl,  74.5.— This  body  may  be 
uced  either  by  exposing  metallic  potassium  to  chlorine 
in  which  case  the  two  elements  unite  together  direct 
or  by  dissolving  caustic  potash  in  chlorhydric  acid, 
n  the  latter  case  water  is  also  formed,  as  is  expressed  by 
the  equation  K  HO    +   H  Cl  =    K  Cl    +    H2O. 

Chloride  of  potassium  closely  resembles  common  salt 
(chloride  of  sodium)  in  appearance,  solubility  in  \ttlfer, 
taste,  etc.  It  is  but  rarely  an  article  of  commerce,  jfK  is 
present  in  the  ash  and  in  the  juices  of  plants,  especially  of 
§ea-weeds,  and  is  likewise  found  in  all  fertile  soils. 


ana 

1 


136  HOW   CROPS   GROW. 

Chloride  of  Sodium,  Na  Cl,  58.5— This  substance  is 
common  or  culinary  salt.  It  was  formerly  termed  muriate 
of  soda.  It  is  scarcely  necessary  to  speak  of  its  occur 
rence  in  immense  quantities  in  the  water  of  the  ocean,  in 
saline  springs,  and  in  the  solid  form  as  rock-salt,  in  the 
earth.  Its  properties  are  so  familiar  as  to  require  no  de 
scription.  It  is  rarely  absent  from  the  ash  of  plants. 

Besides  the  salts  and  compounds  just  described,  there 
occur  in  the  living  plant  other  substances,  most  of  which 
have  been  indeed  already  alluded  to,  but  may  be  noticed 
again  connectedly  in  this  place. 

These  compounds,  being  destructible  by  heat,  do  not 
appear  in  the  analysis  of  the  ash  of  a  plant. 

NITRATES  :  Nitric  acid — the  compound  by  which  nitro 
gen  is  chiefly  furnished  to  plants  for  the  elaboration  of  the 
albuminoid  principles — is  not  unfrequently  present  as  a 
nitrate  in  the  tissues  of  the  plant.  It  usually  occurs  therti 
as  Nitrate  of  Potash,  (niter,  saltpeter.) 

The  properties  of  this  salt  scarcely  need  description.  1 1 
is  a  white,  crystalline  body,  readily  soluble  in  water,  an<l 
has  a  cooling,  saline  taste.  When  heated  with  carbonaceous 
matters,  it  yields  oxygen  to  them,  and  a  deflagration,  or 
rapid  and  explosive  combustion,  results.  Touch-paper  is 
paper  soaked  in  solution  of  niter,  and  dried.  The  leaves 
of  the  sugar-beet,  sun-flower,  tobacco,  and  some  other 
plants,  have  been  found  to  contain  this  salt.  When  sucl 
vegetables  are  burned,  the  nitric  acid  is  decomposed,  ofte 
with  slight  deflagration,  or  glowing  like  touch-paper, 
the  alkali  remains  in  the  ash  as  carbonate.  The  characte 
of  nitric  acid  and  the  nitrates  will  be  noticed  at  length  in 
another  volume,  "  How  Crops  Feed."  ^ 

^CALATES,  CITRATES,  MALATES,  TARTRATES,  and  salts  of 
ot^Htess  common  organic  acids,  are  generally  to  be  founcL 
in  ^Bkissues  of  living  plants.  On  burning,  the  bases  witn 
whicW;hey  were  in  combination — potash  and  lime  in  moat 
cases— ^e.main  as  carbonates. 


THE   ASH    OF   PLANTS.  137 


SALTS  OP  AMMONIA  exist  in  minute  amount  in 
plants.     What  particular  salts  thus  occur  is  uncertain,  and 
special  notice  of  them  is  unnecessary  in  this  chapter. 

Since  it  is  possible  for  each  of  the  acids  above  described 
to  unite  with  each  of  the  bases  in  one  or  several  propor 
tions,  and  since  we  have  as  many  oxides  and  chlorides  as 
there  are  metals,  and  even  more,  the  question  at  once 
arises  —  which  of  the  60  or  more  compounds  that  may  thus 
be  formed  outside  the  plant,  do  actually  exist  within  it? 
In  answer,  we  must  remark  that  all  of  them  may  exist  in 
the  plant.  Of  these,  however,  but  few  have  been  proved 
to  exist  as  such  in  the  vegetable  organism.  As  to  the 
state  in  which  iron  and  manganese  occur,  we  know  little  or 
nothing,  and  \ve  cannot  assert  positively  that  in  a  given 
plant  potash  exists  as  phosphate,  or  sulphate,  or  carbonate. 
We  judge,  indeed,  from  the  predominance  of  potash  and 
phosphoric  acid  in  the  ash  of  wheat,  that  phosphate  of  pot 
ash  is  a  large  constituent  of  the  grain,  but  of  this  we  are 
not  sure,  though  in  the  absence  of  evidence  to  the  contrary 
we  are  warranted  in  assuming  these  two  ingredients  to  be 
united.  On  the  other  hand,  carbonate  of  lime  and  sul 
phate  of  lime  have  been  discovered  by  the  microscope  in 
the  cells  of  various  plants,  in  crystals  whose  characters 
are  unmistakeable. 

For  most  purposes  it  is  unnecessary  to  know  more  than 
that  certain  elements  are  present,  without  paying  atten 
tion  to  their  mode  of  combination.  And  yet  there  is  choice 
in  the  manner  of  representing  the  composition  of  a  plant 
as  regards  its  ash-ingredients. 

We  do  not,  indeed,  speak  of  the  calcium  or  the  silicon  in 
the  plant,  but  of  lime  and  silica,  because  the  idea  of  these 
rarely  seen  elements  is  much  more  vague,  except  to  the 
chemist,  than  that  of  their  oxides,  with  which  every  one 
is  familiar. 

Again,  we  do  not  speak  of  the  sulphates  or  chlorides, 


138  HOW    CROPS   GROW. 

when  wu  desire  to  make  statements  which  may  be  com 
pared  together,  because,  as  has  just  been  remarked,  we 
cannot  always,  nor  often,  say  what  sulphates  or  what 
chlorides  are  present. 

In  the  paragraphs  that  follow,  which  are  devoted  to 
a  more  particular  statement  of  the  mode  of  occurrence, 
relative  abundance,  special  function^  and  indlspensability 
of  the  fixed  ingredients  of  plants,  will  be  indicated  the 
customary  and  best  method  of  defining  them. 


QUANTITY,  DISTRIBUTION,  AND  VARIATIONS  OF   THE  ASH- 
INGREDIENTS. 

The  ash  of  plants  consists  of  the  various  fixed  acids, 
oxides,  and  salts,  noticed  in  §  1. 

The  ash-ingredients  are  always  present  in  each  cell  of 
every  plant. 

The  ash-ingredients  exist  partly  in  the  cell-wall,  in- 
crusting  or  imbedded  in  the  cellulose,  and  partly  in  the 
plasma  or  contents  of  the  cell,  (see  p.  224.) 

One  portion  of  the  ash-ingredients  is  soluble  in  water, 
and  occurs  in  the  juice  or  sap.  This  is  true,  in  general, 
of  the  salts  of  the  alkalies,  and  of  the  sulphates  and 
chlorides  of  magnesium  and  calcium.  Another  portion  is 
insoluble,  and  exists  in  the  tissues  of  the  plant  in  the 
solid  form.  Silica,  the  phosphates  of  lime,  and  the  mag 
nesia  compounds,  are  mostly  insoluble. 

The  ash-ingredients  may  be  separated  from  the  volatile 
matter  by  burning  or  by  any  process  of  oxidation.  In 
burning,  portions  of  sulphur,  chlorine,  alkalies,  and  phos 
phorus,  may  be  lost  under  certain  circumstances,  by  vola« 
tilization.  The  ash  remains  as  a  skeleton  of  the  plant, 
and  often  actually  retains  and  exhibits  the  microscopic 
form  of  the  tissues. 

The  Proportion  of  Ash  is  not  invariable,  even  in  the 


THE    ASH    OF    PLANTS. 


139 


same  kind  of  plant,  and  in  the  same  part  of  the  plant. 
Different  kinds  of  plants  often  manifest  very  marked  differ 
ences  in  the  quantity  of  ash  they  contain.  The  following 
table  exhibits  the  amount  of  ash  in  100  parts,  '(of  dry  mat 
ter,)  of  a  number  of  plants  and  trees,  and  in  their  several 
parts.  In  all  cases  is  given  the  average  proportion,  as  de 
duced  from  a  large  number  of  the  most  trustworthy  exam 
inations.  In  some  instances  are  cited  the  extreme  propor 
tions  hitherto  put  on  record. 

PROPORTIONS  OF  ASH  IN  VARIOUS  VEGETABLE  MATTERS. 

ENTIRE  PLANTS,  BOOTS  EXCEPTED. 

average  average 

Red  clover 6.7      Turnips,  10.7—19.7 15.5 

White"      7.2      Carrot,  15.0-21.3 17.1 

Timothy 7.1      Hops 9.9 

Potatoes 5.1      Hemp  4.6 

Sugar  beet,  16.3—18.6 17.5      Flax 4.3 

Field  beet,  14.0—21.8 18.2      Heath 4.5 

BOOTS  AND  TUBERS. 

Potato,  2.6—8.0 4.1      Turnip,  6.0—20.9 12.0 

Sugar  beet,  2.9—6.0 4.4     Carrot,  5.1—10.9 8.2 

Field  beet,  2.8— 11.3 7.7     Artichoke 5.2 

STRAW  AND  STEMS. 

Wheat,  3.8-6.9 5.4  Peas,  6.5—9.4 7.9 

Rye,  4.9—5.6 5.3  Beans,  5.1—7.2 6.1 

Oats,  5.0—6.4 5.3  Flax 3.7 

Barley 6.8  Maize 5.5 

GRAINS  AND  SEED. 

Wheat,  1.5—3.1 2.0  Buckwheat,  1.1—2.1 1.4 

Rye,  1.6—2.7 2.0  Peas,  2.4— 2.9 2.7 

Oats,  2.5—4.0 3.3  Beans,  2.7—4.3  3.7 

Barley,  1.8—2.8 2.3  Flax 3.6 

Maize,  1.3—2.1 1.5  Sorghum 1.9 

WOOD. 

Beech 1.0  Red  Pine 0.3 

Birch 0.3  White  Pine 0.3 

G-  ape 2.7  Fir 0.3 

Apple 1.3  Larch 0.3 

BARK. 

Birch 1.3  Fir 2.0 

Red  pine 2.8  Walnut 6.4 

White  pine 3.3  Cauto  tree 34.4 


140  HOW   CROPS   GROW. 

From  tlie  above  table  we  gather: — 

1.  That  different  plants  yield  different  quantities  of  ash. 
It  is  abundant  in  succulent  foliage,  like  that  of  the  beet, 
(18  per  cent*)  and  small  in  seeds,  wood,  and  bark. 

2.  That  different  parts  of  the  same  plant  yield  unlike 
proportions  of  ash.     Thus  the  wheat  kernel  contains  2  per 
cent,  while  the  straw  yields  5.4  per  cent.     The  ash  in  su 
gar-beet  tops  is  17.5 ;  in  the  roots,  4.4  per  cent.     In  the 
ripe  oat,  Arendt  found    (Das    Wachsthum  der    Hafer- 
pflanze,  p.  84,) 

In  the  three  lower  joints  of  the  stem. ...  4.6  per  cent  of  ash 
In  the  two  middle  joints  of  the  stem....  5.3 

In  the  one  upper  joint  of  the  stem 6.4 

In  the  three  lower  leaves 10.1 

In  the  two  upper  leaves 10.5 

In  the  ear 2.6 

3.  We  further  find,  that  in  general,  the  upper  and  outer 
parts  of  the  plant  contain  the  most  ash-ingredients.      In 
the  oat,  as  we  see  from  the  above  figures  of  Arendt,  the  ash 
increases  from  the  lower  portions  to  the  upper,  until  we 
reach  the  ear.     If,  however,  the  ear  be  dissected,  we  shall 
find  that  its  outer  parts  are  richest  in  ash.     Norton  found 

In  the  husked  kernels  of  brown  oats,. ..  2.1  per  cent  of  ash 

In  the  husk  of  brown  oats 8.2      u  " 

In  the  chaff  of  brown  oats 19.1      "  " 

Norton  also  found  that  the  top  of  the  oat-leaf  gave  16.22 
per  cent  of  ash,  while  the  bottom  yielded  but  13.66  per 
cent.  (Am.  Jour.  Science,  Vol.  3, 1847.) 

From  the  table  it  is  seen  that  wood,  (0.3  to  2.7  per  cent,) 
and  seeds,  (1.5  to  3.7  per  cent,)  (lower  or  inner  parts  of 
the  plant,)  are  poorest  in  ash.  The  stems  of  herbaceous 
plants,  (3.7  to  7.9  per  cent,)  are  next  richer,  while  the 
leaves  of  herbaceous  plants,  which  have  such  an  extent  of 
surface,  are  the  richest  of  all,  (6  to  8  per  cent.) 

4.  Investigation  has  demonstrated  further  that  the  same 
plant  in  different  stages  of  growth  varies  in  the  proper- 


THE    ASH    OF   PLANTS. 

tions  of  ash  in  dry  matter,  yielded  bol 
plant  and  by  the  several  organs  or  parts.  „  v  ^ 

The  following  results,  obtained  by  Norton,  on  the  oat, 
illustrate  this  variation.      Norton  examined  the  various 
parts  of  the  oat-plant  at  intervals  of  one  week  ' " 
its  entire  period  of  growth.     He  found: 

Leaves.         Stem.       Knots.       Chaff.  Grain  unhusked» 

June    4 10.8  10.4 

June  11 10.7  9.8 

June  18 9.0  9.3 

June25 10.9  9.1 

July    2 11.3  7.8  ..  ..  4.9 

July    9 12.2  7.8  ..  ..  4.3 

July  16 12.6  7.9  ..  6.0  3.3 

July  23 16.4  7.9          10.0  9.1  3.6 

July  30 16.4  7.4  9.6  12.2  4.2 

Aug.    6 16.0  7.6          10.4  13.7  4.3 

Aug.  13 20.4  6.6          10.4  18.6  4.0 

Aug.  20 21.1  6.6          11.7  21.0  3.6 

Aug.  27 22.1  7.7          11.2  22.4  3.5 

Sept.   3 20.9  8.3          10.7  27.4  3.6 

Here,  in  case  of  the  leaves  and  chaff,  we  observe  a  con 
stant  increase  of  ash,  while  in  the  stem  there  is  a  constant 
decrease,  except  at  the  time  of  ripening,  when  these  rela 
tions  are  reversed.  The  knots  of  the  stem  preserved  ,a 
pretty  uniform  ash-content.  The  unhusked  grain  at  first 
suffered  a  diminution,  then  an  increase,  and  lastly  a  de 
crease  again. 

Arendt  found  in  the  c/at-plant  fluctuations,  not  in  all  re 
spects  accordant  with  those  observed  by  Norton.  Arendt 
obtained  the  following  proportions  of  ash : 


3  lower 

2  middle 

Upper 

Lower 

Upper 

Ears. 

Entire 

joints  of 

joints  of 

joint  of 

leaves. 

leaves. 

plant. 

stem. 

stem. 

xtem. 

June  18 

....4.4 

.. 

9.7 

7.7 

.. 

8.0 

June  30 

....2.5 

2.9 

3.5 

9.4 

7.0 

3.8 

5.2 

July  10 

....3.5 

4.7 

5.2 

10.2 

6.9 

3.6 

5.4 

July  21 

....4.4 

5.0 

5.5 

10.1 

9.7 

2.8 

5.2 

July  31 

....6.4 

5.3 

6.4 

10.1 

10.5 

2.6 

5.1 

Here  we  see  that  the  ash  increased  in  the  stem  and  in 
sach  of  its  several  parts  after  the  first  examination.     The 


C 


142  HOW   CROPS   GROW. 

lower  leaves  exhibited  an  increase  of  fixed  matters  after 
the  first  period,  while  in  the  upper  leaves  the  ash  dimin 
ished  toward  the  third  period,  and  thereafter  increased.  In 
the  ears,  and  in  the  entire  plant,  the  ash  decreased  quite 
regularly  as  the  plant  grew  older.  Pierre  found  that  tLe 
proportion  of  ash  of  the  colza,  (Brassica  oleracea,)  dimin 
ished  in  all  parts  of  the  plant,  (which  was  examined  at  fiv^ 
periods,)  except  in  the  leaves,  in  which  it  increased. 
(Jahresbericht  uber  Agriculturchemie,  III,  p.  122.)  The 
sugar  beet,  (Bretschneider,)  and  potato,  (Wolff,)  exhibit 
a  decrease  of  the  per  cent  of  ash,  both  in  tops  and  roots. 

In  the  turnip,  examined  at  four  periods,  Anderson, 
(Trans.  High,  and  Ag.  Soc.,  1859— 61,jt>.  371,)  found  the 
following  per  cent  of  ash  in  dry  matter : 

July  7.      Aug.  11.     Sept.  1.       Oct.  5. 

Leaves 7.8  20.6  18.8  16.2 

Bulbs 17.7  8.7  10.2  20.9 

In  this  case,  the  ash  of  the  leaves  increased  during  about 
half  the  period  of  growth  from  7.8  to  20.6,  and  thence  di 
minished  to  16.2.  The  ash  of  the  bulbs  fluctuated  in  the  re* 
verse  manner,  falling  from  17.7  to  8.7,  then  rising  again  to 
20.9. 

In  general,  the  proportion  of  ash  of  the  entire  plant 
diminishes  regularly  as  the  plant  grows  old. 

5,  The  influence  of  the  sollm  causing  the  proportion  of 
ash  of  the  same  kind  of-  plant  to  vary,  is  shown  in  the  fol 
lowing  results,  obtained  by  Wunder,  (  Versuchs-Stationen, 
IV,  p.  266,)  on  turnip  bulbs,  raised  during  two  successive 
years,  in  different  soils. 

In  sandy  soil.  In  loamy  sott. 

1st  year.    2d  year.        1st  year.    2d  year. 
Per  cent  of  ash....  13.9  11.3  9.1  10.9 

6.  As  might  be  anticipated,  different  varieties  of  the 
Btune  plant,  grown  on  the  same  soil,  take  up  different 
quantities  of  non-volatile  matters. 

In  five  varieties  of  potatoes,  cultivated  in  the  same  soil 


THE    ASH    OF   PLANTS.  143 

and  under  the  same  conditions,  Herapath,  (Qu*  Jour. 
Chem.  Soc.,  II,  p.  20,)  found  the  percentages  of  ash  in 
dry  matter  of  the  tuber  as  follows : 

Variety  of  potato.  White       Prince's      Axbridge       Magpie.      Forty~ 

Apple.        Beauty.       Kidney.  fold. 

Ash  per  cent 4.8  3.6  4.3  3.4  3.9 

7«  It  has  been  observed  further  that  different  individuals 
of  the  same  variety  of  plant,  growing  side  by  side,  on  the 
same  soil,  (in  the  same  field  at  least,)  contain  different  pro 
portions  of  ash-ing redients,  according  as  they  are,  on  the 
one  hand,  healthy,  vigorous  plants,  or,  on  the  other,  weak 
and  stunted.  Pierre,  (Jahresbericht  uber  Agriculturchemie, 
III,  p.  125,)  found  in  entire  colza  plants  of  various  degrees 
of  vigor  the  following  percentages  of  ash  in  dry  matter: 

In  extremely  feeble  plants,  1856 8.0  per  cent  of  ash 

In  very  feeble  plants,  1857 9.0      "  " 

In  feeble  plants,  1857 11.4      "  " 

In  strong  plants,  1857 11.0      "  " 

In  extremely  strong  plants,  ia57 14.3      "  " 

Pierre  attributes  the  larger  per  cent  of  ash  in  the  strong 
plants  to  the  relatively  greater  quantity  of  leaves  devel 
oped  on  them. 

Similar  results  were  obtained  by  Arendt  in  case  of  oats. 
Wunder,  ( Versuchs-St.,  IV,  p.  115,)  found  that  the  leaves 
of  small  turnip  plants  yielded  somewhat  more  ash,  per 
cent,  than  large  plants.  The  former  gave  19.7,  the  latter 
16.8  per  cent. 

8.  The  reader  is  prepared  from  several  of  the  foregoing 
statements  to  understand  partially  the  cause  of  the  varia 
tions  in  the  proportion  of  ash  in  different  specimens  of  the 
same  kind  of  plant. 

The  fact  that  different  parts  of  the  plant  are  unlike  in 
their  composition,  the  upper  and  outer  portions  being,  in 
general,  the  richer  in  ash-ingredients,  may  explain  in  some 
degree  why  different  observers  have  obtained  different 
analytical  results. 

It  is  well  known  that  a  variety  of  circumstances  in- 


144  HOW   CROPS   GROW. 

fluences  tne  relative  development  of  the  organs  of  a  plant. 
In  a  dry  season,  plants  remain  stunted,  are  rougher  on  the 
surface,  have  more  and  harsher  hairs  and  prickles,  if  these 
belong  to  them  at  all,  and  develope  fruit  earlier  than 
otherwise.  In  moist  weather,  and  under  the  influence  of 
rich  manures,  plants  are  more  succulent,  and  the  stems  and 
foliage,  or  vegetative  parts,  grow  at  the  expense  of  the  re 
productive  organs.  Again,  different  varieties  of  the  same 
plant,  which  are  often  quite  unlike  in  their  style  of  devel 
opment,  are  of  necessity  classed  together  in  our  table,  and 
under  the  same  head  are  also  brought  together  plants 
gathered  at  different  stages  of  growth. 

In  order  that  the  wheat  plant,  for  example,  should  always 
have  the  same  percentage  of  ash,  it  would  be  necessary 
that  it  should  always  attain  the  same  relative  development 
in  each  individual  part.  It  must,  then,  always  grow  under 
the  same  conditions  of  temperature,  light,  moisture,  and 
soiL  This  is,  however,  as  good  as  impossible,  and  if  we 
admit  the  wheat  plant  to  vary  in  form  within  certain  lim 
its  without  losing  its  proper  characteristics,  we  must  ad 
mit  corresponding  variations  in  composition. 

The  difference  between  the  Tuscan  wheat,  which  is  cul 
tivated  exclusively  for  its  straw,  of  which  the  Leghorn 
hats  are  made,  and  the  "  pedigree  wheat "  of  Mr.  Hallett, 
(Journal  Roy.  Ag.  Soc.  ofJEJng.,  Vol.  22, p.  374,)  is  in  some 
respects  as  great  as  between  two  entirely  different  plants. 
The  hat  wheat  has  a  short,  loose,  bearded  ear,  containing 
not  more  than  a  dozen  small  kernels,  while  the  pedigree 
wheat  has  shown  beardless  ears  of  8J  inches  in  length, 
closely  packed  with  large  kernels  to  the  number  of  120 ! 

Now,  the  hat  wheat,  if  cultivated  and  propagated  in  the 
game  careful  manner  as  has  been  done  with  the  pedigree 
wheat,  would,  no  doubt,  in  time  become  as  prolific  of  grain 
as  the  latter,  while  the  pedigree  wheat  might  perhaps  with 
greater  ease  be  made  more  valuable  for  its  straw  than  its 
grain. 


THE   ASH    OF   PLANTS.  145 

We  easily  see  then,  that,  as  circumstances  are  perpetual 
ly  making  new  varieties,  so  analysis  continually  finds  di 
versities  of  composition. 

0,  Of  all  the  parts  of  plants  the  seeds  are  the  least  liable 
to  vary  in  composition.  Two  varieties  or  two  individuals 
may  differ  enormously  in  their  relative  proportions  of 
foliage,  stem,  chaff,  and  seed;  but  the  seeds  themselves 
nearly  agree.  Thus,  in  the  analyses  of  67  specimens  of 
the  wheat  kernel,  collated  by  the  author,  the  extreme 
percentages  of  ash  were  1.35  and  3.13.  In  60  specimens 
out  of  the  67,  the  range  of  variation  fell  between  1.4  and 
2.3  per  cent.  In  42  the  range  was  from  1.7  to  2.1  per 
cent,  while  the  average  of  the  whole  was  2.1  per  cent. 

In  the  stems  or  straw  of  the  grains,  the  variation  is  much 
more  considerable.  Wheat-straw  ranges  from  3.8  to  6.9 ; 
pea-straw,  from  6.5  to  9.4  per  cent.  In  fleshy  roots,  the 
variations  are  great;  thus  turnips  range  from  6  to  21  per 
cent.  The  extremest  variations  in  ash-content  are,  how 
ever,  found,  in  general,  in  the  succulent  foliage.  Turnip 
tops  range  from  10.7  to  19.7;  potato  tops  vary  from  11  to 
near  20,  and  tobacco  from  19  to  27  per  cent. 

Wolff,  (Die  naturgesetzlichen  Grundlagen  des  Acker- 
baues,  3.  Aufl.,  p.  117,)  has  deduced  from  a  large  number 
of  analyses  the  following  averages  for  three  important 
classes  of  agricultural  plants,  viz.: 

Grain.  Straw. 

Cereal  crops  2  5.25  per  cent. 

Leguminous  crops      3  5         "       " 

Oil-plants  4  4.5      "       " 

More  general  averages  are  as  follows,  (Wolff  loc.  cit.) : 


Annual  and  biennial  plants. 
Seeds       -    -    -     3  per  cent 
Stems    -    ...  5     "     " 
Roots      -    -    -     4 
Leaves  -     .    -     15 
7 


"     " 


Perenn  ial  plants. 
Seeds       ...    3  per  cent 
Wood-    -    -    -   1     "     " 
Bark      ...      7     "     " 
Leaves     -    -    -  XO    '<    w 


146  HOW   CROPS    GROW. 

We  may  conclude  this  section  by  stating  three  proposi 
tions  which  are  proved  in  part  by  the  facts  that  have  been 
already  presented,  and  which  are  a  summing  up  of  the 
most  important  points  in  our  knowledge  of  this  subject. 

I.  Ash-ingredients  are  indispensable  to  the  life  and 
growth  of  all  plants.  In  mold,  yeast,  and  other  plants  of 
fife  simplest  kind,  as  well  as  in  those  of  the  higher  orders, 
analysis  never  fails  to  recognize  a  proportion  of  fixed  mat 
ters.  We  must  hence  conclude  that  these  are  necessary  to 
the  primary  acts  of  vegetation,  that  atmospheric  food  can 
not  be  assimilated,  that  vegetable  matter  cannot  be  organ 
ized,  except  with  the  cooperation  of  those  substances,  which 
are  found  in  the  ashes  of  the  plant.  This  proposition  is 
demonstrated  further  in  the  most  conclusive  manner  by 
numerous  synthetic  experiments.  It  is,  of  course,  impos 
sible  to  attempt  producing  a  plant  at  all  without  some  ash- 
ingredients,  for  the  latter  are  present  in  all  seedsxand  dur 
ing  germination  are  transferred  to  the  seedling.  By  caus 
ing  seeds  to  sprout  in  a  totally  insoluble  medium,  we  can 
observe  what  happens  when  the  limited  supply  of  fixed 
matters  in  the  seeds  themselves  is  exhausted.  Wiegmann 
&  Polstorf,  (Preisschrift  uber  die  unorganischen  Bestand- 
thelle  der  Pflanzen,)  planted  30  seeds  of  cress  in  fine  plati 
num  wire  contained  in  a  platinum  vessel.  The  contents 
of  the  vessel  were  moistened  with  distilled  water,  and  the 
whole  was  placed  under  a  glass  shade,  which  served  to 
shield  from  dust.  Through  an  aperture  in  the  shade,  con 
nection  was  made  with  a  gasometer,  by  which  the  atmos 
phere  in  the  interior  could  be  renewed  with  an  artificial  mix 
ture,  consisting  in  100,  of  21  parts  oxygen,T8  parts  nitrogen, 
and  1  part  carbonic  acid.  In  two  days  '28  of  the  seeds 
germinated;  afterwards  they  developed  leaves,  and  grew 
slowly -with  a  healthy  appearance  during  26  days,  reaching 
a  height  of  two  to  three  inches.  From  this  time  on,  they 
refused  to  grow,  begun  to  turn  yellow,  and  died  down. 
The  plants  were  collected,  and  burned ;  the  ash  from  them 


THE  ASH   OP   PLANTS.  147 

weighed  precisely  as  much  as  that  obtained  by  burning  28 
seeds  like  those  originally  sown.  This  experiment  demon 
strates  most  conclusively  that  a  plant  cannot  grow  in  the 
absence  of  those  substances  found  in  its  ash.  The  devel 
opment  of  the  cresses  ceased  so  soon  as  the  fixed  matters 
of  the  seed  had  served  their  utmost  in  assisting  the  organ 
ization  of  new  cells.  We  kno\v  from  other  experiments 
that,  had  the  ashes  of  cress  been  applied  to  the  plants  in 
the  above  experiment,  just  as  they  exhibited  signs  of  un- 
healthiness,  they  would  have  recovered,  and  developed  to 
a  much  greater  extent. 

II.  The  proportion  of  ash-ingredients  in  the  plant  is  va 
riable  within  a  narrow  range  ;  but  cannot  fall  below  or 
exceed  certain  limits.  The  evidence  of  this  proposition  is  to 
be  gathered  both  from  the  table  of  ash-percentages,  and 
from  experiments  like  that  of  Wiegmann  &  Polstorf  above 
described. 

Ill*  We  have  reason  to  believe  that  each  part  or  organ, 
(each  cell,)  of  the  plant  contains  a  certain,  nearly  invari 
able  amount  of  fixed  matters,  which  is  indispensable  to  the 
vegetative  functions.  Each  part  or  organ  may  contain,  be 
sides,  a  variable  and  unessential  or  accidental  quantity  of 
the  same.  What  portion  of  the  ash  of  any  plant  is  essen 
tial  and  what  accidental  is  a  question  not  yet  brought 
to  a  satisfactory  decision.  By  assuming  the  truth  of  this 
proposition,  we  account  for  those  variations  in  the  amount 
of  ash  which  cannot  be  attributed  to  the  causes  already 
noticed.  The  evidences  of  this  statement  must  be  reserv 
ed  for  the  subsequent  section. 

§3. 

SPECIAL  COMPOSITION  OF  THE  ASH  OF  AGRICULTURAL 
PLANTS. 

The  results  of  the  extended  inquiries  which  have  been 
recently  made  into  the  subject  of  this  section  may  be  con* 


J48  HOW   CROPS   GROW. 

veniently  presented  and  discussed  under  a  series  of  propo 
sitions,  viz.: 

1«  Among  the  substances  which  have  been  described, 
(§  1,)  as  the  ingredients  of  the  ash,  the  following  are  in 
variably  present  in  all  agricultural  plants,  and  in  nearly 
nil  parts  of  them,  viz/ 


(  Potash 

Soda 
Bases  -j  Lime  Acide 

Magnesia 
I  Oxide  of  iron 


Chlorine 
Sulphuric  acid 
Phosphoric  acid 
Silicic  acid 


Carbonic  acid 


2.  Different  normal  specimens  of  the  same  kind 
have  a  nearly  constant  composition.  The  use  of  il\ 
nearly  in  the  above  statement  implies  what  has* 
ready  intimated,  viz.,  that  some  variation  is  noticec 
relative  proportions,  as  well  as  in  the  total  quantity  of 
ash-ingredients  occurring  in  plants.  This  point  will 
shortly  be  discussed  in  full.  By  taking  the  average  of 
many  trustworthy  ash-analyses,  we  arrive  at  a  result 
which  does  not  differ  very  widely  from  the  majority  of  the 
individual  analyses.  This  is  especially  true  of  the  seeds 
of  plants,  which  attain  nearly  the  same  development  under 
all  ordinary  circumstances.  It  is  less  true  of  foliage  and 
roots,  whose  dimensions  and  character  vary  to  a  great  ex 
tent.  In  the  following  tables  (p.  150-156)  is  stated  the  com 
position  of  the  ashes  of  a  number  of  agricultural  products, 
which  have  been  repeatedly  subjected  to  analysis.  In 
most  cases,  instead  of  quoting  all  the  individual  analyses, 
a  series  of  averages  is  given.  Of  these,  the  first  is  the 
mean  of  all  the  analyses  on  record  or  obtainable  by  the 
writer,*  while  the  subsequent  ones  represent  either  the  re 
sults  obtained  in  the  examination  of  a  number  of  samples 
by  one  analyst,  or  are  the  mean  of  several  single  anal- 


*  The  numerous  ash-analyses,  published  by  Dr.  E.  Emmons  and  Dr.  J.  II. 
Salisbury,  in  the  Natural  History  of  New  York,  and  in  the  Trans,  of  the  N.  Y. 
S:  i!r  A«j.  Society,  have  been  disregarded  on  account  of  their  manifest  worthless- 
IIO*D  and  absurdity. 


THE    ASH    OF    PLANTS.  149 

yses.  In  this  way,  it  is  believed,  the  real  variations  of 
composition  are  pretty  truly  exhibited,  independently  of 
the  errors  of  analysis. 

The  lowest  and  highest  percentages  are  likewise  given. 
These  are  doubtless  in  many  cases  exaggerated  by  errors 
of  analysis,  or  by  impurity  of  the  material  analyzed. 
Chlorine  and  sulphuric  acid  are  for  the  most  part  too  low, 
because  they  are  liable  to  be  dissipated  in  combustion, 
while  silica  is  often  too  high,  from  the  fact  of  sand  and  soil 
adhering  to  the  plant. 

In  two  cases,  single  and  perhaps  incorrect  analyses  by 
Bichon,  which  give  exceptionally  large  quantities  of  soda, 
are  cited  separately. 

A  number  of  analyses  that  came  to  notice  after  making 
out  the  averages,  are  given  as  additional. 

The  following  table  includes  both  the  kernel  and  straw 
of  Wheat,  Rye,  Barley,  Oats,  Maize,  Rice,  Buckwheat, 
Beans,  and  Peas ;  the  tubers  of  Potatoes ;  the  roots  and 
tops  of  Sugar  Beets,  Field  Beets,  Carrots,  Turnips,  and 
various  parts  of  the  Cotton  Plant. 

For  the  average  composition  of  other  plants  and  vege 
table  products,  the  reader  is  referred  to  a  table  in  the  ap 
pendix,  p.  376,  compiled  by  Prof.  Wolff,  of  the  Royal 
Agricultural  Academy  of  Wurtemberg.  That  table  in 
cludes  also  the  averages  obtained  by  Prof.  Wolff  for  most  of 
the  substances,  cotton  excepted,  whose  composition  is  rep 
resented  in  the  pages  immediately  following.  Any  dis 
crepancies  between  Prof.  Wolff's  and  the  author's  figures 
are  for  the  most  part  due  to  the  use  of  fewer  analyses  by 
the  former. 

In  both  tables,  the  carbonic  acid,  which  occurs  in  most 
ashes,  is  excluded,  from  the  fact  that  its  quantity  varies 
according  to  the  temperature  at  which  the  ash  is  pre 
pared. 


150 


HOW   CROPS   GROW. 


THE    ASU    OF   PLANTS. 


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HOW   CROPS    GROW. 


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THE    ASH    OF   PLANTS. 


153 


TRAW. 
Average  of  5  Analyses.* 
Lowest  percentage  in  5  Analyses. 
Highest  "  5  "  [above. 
Recent  incomplete  Anal,  by  Henneberg  &  Stohmann  not  included 
STRAW. 

Average  of  17  Analyses. 
4  "  byZoeller. 
"  5  "  "  Way  &  Ogston. 
"  8  "  "  Wolff. 
Lowest  percentage  in  9  Analyses,  Wolff's  excluded. 
Highest  "  9 
TRAW.  - 

Average  of  5  Analyses. 
3  "  by  Way  &  Ogston. 
2  "  "  Levi,  and  Boussingault. 
Lowest  percentage  in  5  Analyses. 
Highest  "  5 
Recent  Analysis  by  Henneberg  &  Stohmann,  not  included  above. 
STALKS. 

|Way  &  Ogston. 

EAT  STRAW. 

Average  of  6  Analyses  by  Wolff. 
TRAW. 

Average-  of  22  Analyses. 
13  "  for  Prussian  Landes  Oec.  Collegiunxt 
6  "  by  Way  &  Ogston. 

"  3  "  4t  others.J 
Lowest  percentage  in  22  Analyses. 
Highest  "  22 
Analysis  by  Bacr.§ 

By  Rammelsberg,  Nitzsch,  Liebig,  Marcband,  StemDerg,  Schulze, 
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;rroueously  copied.  The  next  highest  per  cent  or  Soda  is  15.L 

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154 


HOW   CROPS   GROW. 


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THE    ASH    OF   PLANTS. 


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156 


HOW   CROPS   GROW. 


THE   ASU    OF   PLANTS. 


The  composition  of  the  ash  of  a  num 
crops  is   concisely  exhibited   in  the  subjo 
statement. 


Alkalies. 


Mag- 


Sulphurs 
Acid. 


CEREALS  — 

Grain*.... 

30 

12 

3 

46 

2 

2.5 

1 

Straw 

13—27 

3 

7 

5 

50_70 

2.5 

2 

LEGUMES— 

Kernel  .  .  . 

44 

7 

5 

35 

1 

4- 

2 

Straw  

27—41 

7 

25-39 

8 

5 

2—6 

6—7 

ROOT  CROPS— 

Roots  

60 

3—9 

6—12 

8—18 

1--4 

5—12 

3—9 

Tops  

37 

3—16 

10—35 

3—8 

3 

6—13 

5—17 

GRASSES  — 

In  flower.  . 

33 

4 

8 

8 

35 

4 

5 

3.  Different  parts  of  any  plant  usually  exhibit  decided 
differences  in  the  composition  of  their  ash.  This  fact  is 
made  evident  by  a  comparison  of  the  figures  of  the  table 
above,  and  is  more  fully  illustrated  by  the  following  anal 
yses  of  the  parts  of  the  mature  oat-plant,  by  Arendt,  1  to  6, 
(Die  JETaferpflanze^p.  107,)  and  Norton,  7  to  9,  (Am.  Jour. 
Sci.,  2  Ser.  3,  318.) 


Stem. 
Potash  ................  81.2 

Soda  ..................  0.4 

Magnesia  ............  2.1 


123456789 
Lower  Middle  Upper  Lower  Upper  Ears.  Chaff.  Husk. Kernel 


I-ime 

Oxide  of  Iron  ....... 

Phosphoric  acid  ..... 

Suli  huric  acid  ....... 

Sillei 


3.6 
1.0 
2.7 
0.0 
4.1 


Chlorine  ..............  8.6 


Stem. 

68.3 
1.5 
3.6 
5.3 
0.0 
1.4 
1.3 
9.3 

11.7 


Stem.  Leaves. Leaves. 
55.9      36.9    -24.8 

0.9 

3.8 
16.7 

2.7 

1.7 

3.2 
34.0 

1.6 


1.0 
3.9 

8.6 
0.2 
2.7 
1.1 
20.4 
7.4 


0.4 
3.9 

17.2 
0.5 
1.5 
7.5 

41.8 
2.4 


13.0    t-m  « 

o.i  f10-6 

8.9  1 

7.3  L,  2 
trace  fU-S 
36.5  J 

4.9  5.3 
26.0  68.0 

3.8       3.1 


husked. 
12.4     31.7 


2.3 
4.3 
0.3 
0.6 
4.3 
74.1 
1.4 


8.6 
5.3 
0.8 
49.1 
0.0 
1.8 
0.2 


The  results  of  Arendf  and  Norton  are  not  in  all  respects  strictly  com 
parable,  having  been'  obtained  by  different  methods,  but  serve  well  to 
establish  the  fact  in  question. 

We  see  from  the  above  figures  that  the  ash  of  the  lower\ 
stem  consists  chiefly  of  potash,  (81  °|  0.)    This  alkali  is  pre-  * 
dominant  throughout  the  stem,  but  in  the  upper  parts, 
where  the  stem  is  not  covered  by  the  leaf  sheaths,  silica. 
and  lime  occur  in  large  quantity.    In  the  asb  )f  the  leases, 


*  Exclusive  o\  huak. 


158  HOW   CROPS   GROW. 

silica,  potash,  and  lime,  are  the  principal  ingredients.  In 
the  chaff  and  husk,  silica  constitutes  three-fourths  of  the 
ash,  while  in  the  grain,  phosphoric  acid  appears  as  the 
characteristic  ingredient,  existing  there  in  connection  with 
a  large  amount  of  potash,  (32  °|0,)  and  considerable  mag 
nesia.  Chlorine  acquires  its  maximum,  (11.7°|0,)in  the 
middle  stem,  but  in  the  kernel  is  present  in  small  quantity, 
while  sulphuric  acid  is  totally  wanting  in  the  lower  stem, 
and  most  abundant  in  the  upper  leaves. 

Again,  the  unequal  distribution  of  the  ingredients  of 
the  ash  is  exhibited  in  the  leaves  of  the  sugar  beet,  which 
have  been  investigated  by  Bretschneider,  (Soff.  Jahresbe- 
richt,  4,  89.)  This  experimenter  divided  the  leaves  of  6 
sugar  beets  into  5  series  or  circles,  proceeding  from  the 
outer  and  older  leaves  inward.  He  examined  each  series 
separately  with  the  following  results : 

i.          n.        m.        rv.         v. 

Potash 18.7  25.9  32.8  37.4  50.3 

Soda 15.2  14.4  15.8  15.0  11.1 

Chloride  of  Sodium...  5.8  6.4  5.8  6.0  6.6 

Lime...  24.2  19.2  18.2  15.8  4.7 

Magnesia 24.5  22.3  13.0  8.9  6.7 

Oxide  of  Iron 1.4  0.5  0.6  0.6  0.5 

Phosphoric  acid 3.3  4.8  5.8  8.4  12.7 

Sulphuric  acid .5.4  5.6  B.6  5.2  6.9 

Silica 1.5  0.8  2.7  2.1  1.5 

From  these  data  we  perceive  that  in  the  ash  of  the 
leaves  of  the  sugar  beet,  potash  and  phosphoric  acid  reg 
ularly  and  rapidly  increase  in  relation  to  the  other  ingre 
dients  from  without  inward,  while  lime  and  magnesia  as 
rapidly  diminish  in  the  same  direction.  The  per  cent  of 
the  other  ingredients,  viz.,  soda,  chlorine,  oxide  of  iron, 
sulphuric  acid,  and  silica,  remains  nearly  invariable 
throughout. 

Another  illustration  is  furnished  by  the  following  anal 
yses  of  the  ashes  of  the  various  parts  of  the  horse-chestnut 
tree,  made  by  Wolff,  (Ackerbau,  2.  Auf.,  134) 


THE  ASH    OF   PLANTS.                                      159 

Bark.  Wood.  Leaf -stems.  Leavtt.  Flower-stems.  Calyx. 

Potash 12.1  25.7           46.2           27.9           63.6           61.7 

Lime 76.8  42.9           21.7           29.3             9.3           12.3 

Magnesia 1.7  5.0            3.0            2.6            1.3            5.9 

Sulphuric  acid trace  trace           3.8            9.1            3.5          trace 

Phosphoric  acid 6.0  19.2          14.8           22.4           17.1           16.6 

Silica 1.1  2.6            1.0            4.9            0.7            1.7 

Chlorine 2.8  6.1           12.2            5.1            4.7            2.4 

Ripe  Fruit. 


Stamens  Petals.  Green  Fruit.  Kernel.  Green  Brown 

SMI.  Sfiett. 

Potash 60.7  61.2          58.7  61.7  75.9  54.6 

Lime 13.8  13.6             9.8  11.5  8.6  16.4 

Magnesia 3.1  3.8            2.4            0.6  1.1  2.4 

Sulphuric  acid trace  trace           3.7            1.7  1.0  3.6 

Phosphoric  acid  ....19.5  17.0           20.8  22.8  5.3  18.6 

Silica 0.7  1.5            0.9            0.2  0.6  0.8 

Chlorine 2.8  3.8            4.8            2.0  7.6  5.2 

4t  Similar  kinds  of  plants ,  and  especially  the  same 
parts  of  similar  plants,  exhibit  a  close  general  agreement 
in  the  composition  of  their  ashes  •  while  plants  which  are 
unlike  in  their  botanical  characters  are  also  unlike  in  the 
proportions  of  their  fixed  ingredients. 

The  three  plants,  wheat,  rye,  and  maize,  belong,  botanical- 
ly  speaking,  to  the  same  natural  order,  grammece,  and  the 
ripe  kernels  yield  ashes  almost  identical  in  composition. 
Barley  and  the  oat  are  also  graminaceous  plants,  and  their 
seeds  should  give  ashes  of  similar  composition.  That  such 
is  not  the  case  is  chiefly  due  to  the  fact,  that,  unlike  the 
wheat,  rye,  and  maize-kernel,  the  grains  of  barley  and 
oats  are  closely  invested  with  a  husk,  which  forms  a  part 
of  the  kernel  as  ordinarily  seen.  This  husk  yields  an  ash 
which  is  rich  in  silica,  and  we  can  only  properly  compare 
barley  and  oats  with  wheat  and  rye,  when  the  former  are 
hulled,  or  the  ash  of  the  hulls  is  taken  out  of  the  account. 
There  are  varieties  of  both  oats  and  barley,  whose  husks 
separate  from  the  kernel — the  so-called  naked  or  skinless 
oats  and  naked  or  skinless  barley — and  the  ashes  of  these 
grains  agree  quite  nearly  in  composition  with  those  of  wheat, 
rye,  and  maize,  as  may  be  seen  from  the  following  table: 


I  GO 


HOW   CROPS   GROW. 


Wheat. 

Rye. 

Maize. 

SJdrdess 

Sktnte* 

Average 
of 

Average 
of 

Average 
of 

oats. 
Analysis 

barley. 
Analysis 

seventy-nine 
analyse!. 

twenty-one 
analyses. 

seven 
analyses. 

ty/Fr. 
Schulze. 

tnjFr. 
Schulze. 

Potasb  31.3 

28.8 

27.7 

33.4 

35.9 

Soda                      3  2 

4.3 

4.0 

1.0 

Magnesia  12  3 

11.6 

15.0 

11.8 

13.7 

Lime                      3  2 

3.9 

1.9 

3.6 

2.9 

Oxide  of  Iron...  0.7 

0.8 

1.0 

0.8 

0.7 

Phosphoric  acid.  46.1 

45.6 

47.1 

46.9 

45.0 

Sulphuric  acid...  1.2 

1.9 

1.7 

—  _ 



Silica                      1  9 

2.6 

2.1 

2.4 

0.7 

Chlorine...       ,  .  0.2 

0.7 

0.1 

By  reference  to  the  table,  (p.  152,)  it  will  be  observed 
that  the  pea  and  bean  kernel,  together  with  the  allied  vetch 
and  lentil,  (p.  379,) also  nearly  agree  in  ash-composition. 

So,  too,  the  ashes  of  the  root-crops,  turnips,  carrots,  and 
beets,  exhibit  a  general  similarity  of  composition,  as  may 
be  seen  in  the  table,  (p.  154-5). 

The  seeds  of  the  oil-bearing  plants  likewise  constitute  a 
group  whose  members  agree  in  this  respect,  p.  379. 

5*  The  ash  of  the  same  species  of  plant  is  more  or  less 
variable  in  composition,  according  to  circumstances. 

The  conditions  that  have  already  been  noticed  as  in 
fluencing  the  proportion  of  ash  are  in  general  the  same 
that  affect  its  quality.  Of  these  we  may  specially  notice  : 

a.  The  stage  of  growth  of  the  plant. 

b.  The  vigor  of  its  development. 

c.  The  variety  of  the  plant  or  the  relative  development 
of  its  parts,  and 

d.  The  soil  or  the  supplies  of  food. 

a.  The  stage  of  growth.  The  facts  that  the  different 
parts  of  a  plant  yield  ashes  of  different  composition,  and 
that  the  different  stages  of  growth  are  marked  by  the 
development  of  new  organs  or  the  unequal  expansion  of 
those  already  formed,  are  sufficient  to  sustain  the  point 
now  in  question,  and  render  it  needless  to  cite  analytical 
evidence.  In  a  subsequent  chapter,  wherein  we  shall  at 
tempt  to  trace  some  of  the  various  steps  in  the  progressive 


THE    ASH    OF   PLANTS  161 

development  of  the  plant,  numerous  illustrations  will  be 
adduced,  (p.  214.) 

b.  Vigor  of  development.    Arendt,  (Die  Haferpflanze, 
p.  18,)  selected  from  an  oat-field  a  number  of  plants  in 
bl/ssom,  and  divided  them  into  three  parcels — 1,  composed 
of  very  vigorous  plants ;    2,  of  medium ;  and,  3,  of  very 
weak  plants.     He  analyzed  the  ashes  of  each  parcel,  with 
results  as  below : 

123 

Silica 37.0  39.9  42.0 

Sulphuric  acid 4.8  4.1  5.6 

Phosphoric  acid 8.2  8.5  8.8 

Chlorine 6.7  5.8  4.7 

Oxide  of  Iron 0.4  0.5  1.0 

Lime 6.1  5.4  5.1 

Magnesia, Potash*  Soda. 45.3  34.3  30.4 

Here  we  notice  that  the  ash  of  the  weak  plants  contains 
15  per  cent  less  of  alkalies,  and  15  per  cent  more  of  silica, 
than  that  of  the  vigorous  ones,,  while  the  proportion  of  the 
other  ingredients  is  not  greatly  different. 

Zoeller,  (Lieblg^s  Erndhrung  der  Vegetdbilien,  p.  340,) 
examined  the  ash  of  two  specimens  of  clover  which  grew 
on  the  same  soil  and  under  similar  circumstances,  save 
that  one,  from  being  shaded  by  a  tree,  was  less  fully  devel 
oped  than  the  other. 

Six  weeks  after  the  sowing  of  the  seed,  the  clover  waa 
cut,  and  gave  the  following  results  on  partial  analysis : 

Shaded  clover.  Unshaded  clover. 

Alkalies 54.9  36.2 

Lime 14.2  22.8 

Silica 5.5  12.4 

c.  The  variety  of  the  plant  or  the  relative  development 
of  it&  parts  must  obviously  influence  the  composition  of 
the  ash  taken  as  a  whole,  since  the  parts  themselves  are 
unlike  in  composition. 

Herapath,  (Qu.  Jour.  Chem.  &tc.,  II, p.  20,)  analyzed 
the  ashes  of  the  tubers  of  five  varieties  of  potatoes,  raised 
on  the  same  soil  and  under  precisely  similar  circumstances* 
His  results  are  as  follows  : 


Potash 

White 
Apple. 
69  7   ' 

Prince's 
Beauty. 
65  2 

Axbridne 
Kidney. 
70  6 

Chloride  of  Sodium 
Lime  

3  0 

1  8 

5  0 

Magnesia  , 

.  6.5 

5.5 

5.0 

Phosphoric  acid.  .  .  . 
Sulphuric  acid 

17.2 
3  6 

20.8 
6  0 

14.9 
4  3 

Silica  .  . 

0.2 

J62  HOW    CROPS    GROW. 

Magpie.        Forty-fold. 

70.0  62  I 

2  5 

5.0  3.3 

2.1  3.5 
14.4               20.7 

7.5  7.9 

d.  The  soil,  or  the  supplies  of  food,  manures  included, 
have  the  greatest  influence  in  varying  the  proportions  of 
the  ash-ingredients  of  the  plant.  It  is  to  a  considerable 
degree  the  character  of  the  soil  which  determines  the 
vigor  of  the  plant  and  the  relative  development  of  its 
parts.  This  condition  then,  to  a  certain  extent,  includes 
those  already  noticed. 

It  is  well  known  that  oats  have  a  great  range  of  weight 
per  bushel,  being  nearly  twice  as  heavy  when  grown  on 
rich  land,  as  when  gathered  from  a  sandy,  inferior  soil 
According  to  the  agricultural  statistics  of  Scotland,  for  the 
year  1857,  (Trans.  Highland  and  Ag.  }Soc.,  1857 — 9,jt?. 
213,)  the  bushel  of  oats  produced  in  some  districts  weigh 
ed  44  pounds  per  bushel,  while  in  other  districts  it  was  as 
low  as  35  pounds,  and  in  one  instance  but  24  pounds  per 
bushel  Light  oats  have  a  thick  and  bulky  husk,  and  an 
ash-analysis  gives  a  result  quite  unlike  that  of  good  oats. 
Herapath,  (Jour.  Hoy.  Ag.  Society,  XL,  p.  107,)  has  pub 
lished  analyses  of  light  oats  from  sandy  soil,  the  yield  be 
ing  six  bushels  per  acre,  and  of  heavy  oats  from  the  same 
soil,  after  "  warping,"*  where  the  produce  was  64  bushels 
per  acre.  Some  of  his  results,  per  cent,  are  as  follows : 

Light  oats.  Ifeavy  oats. 

Potash 9.8  13.1 

Soda 4.6  7.2 

Lime 6.8  4.2 

Phosphoric  acid...  9.7  17.6 

Silica 50. 5  45.6 

Wolff,  (Jour,  far  Pralct.  Chem.,  52,  p.  103,)  has  anal- 

•  Thickly  coverii  g  with  sediment  from  muddy  tide-water. 


THE   ASH    OF    PLANTS.  163 

ysed  the  ashes  of  several  plant*,  cultivated  in  a  poor  soil, 
with  the  addition  of  various  mineral  fertilizers.  The  in 
fluence  of  the  added  substances  on  the  composition  of  the 
plant  is  very  striking.  The  following  figures  comprise 
his  results  on  the  ash  of  buckwheat  straw,  which  grew  on 
the  unmanured  soil,  and  on  the  same,  after  application  of 
the  substances  specified  below : 


1 
Unma 
nured. 
potash  31.7 

2 

Chloride 
of 
sodium. 
21.0 

3 

Nitrate 
of 
potash. 
39.6 

4 

Carbonate 
of 
potash. 
40.5 

5 

Sulphate 

°f   . 
magnes-to 
28.2 

6 

Carbonate 
of 
;.    hme. 
23.9 

Chloride  of  potassium.  7.4 
Chloride  of  sodium...    4.6 
Lime    15  7 

26.9 
3.0 
14  0 

0.8 
3.2 
12  8 

3.1 
3.8 
11  6 

6.9 
3.4 
14  1 

9.7 
1.7 
18  6 

Ma^ne^ia                      .17 

1  9 

3  3 

1  4 

4  7 

4  2 

Sulphuric  acid  47 

2.8 

2.7 

4.3 

7.1 

3.5 

Phosphoric  acid  ....    10  3 

9  5 

6  5 

8  9 

10  9 

10  0 

Carbonic  acid               20  4 

16  1 

27  1 

22  2 

20  0 

23  2 

Silica  36 

4  2 

4  2 

4  2 

4  8 

5  2 

100.0         100.0         100.0         100.0         100.0         100.0 

It  is  seen  from  these  figures  that  all  the  applications 
employed  in  this  experiment  exerted  a  manifest  influence, 
and,  in  general,  the  substance  added,  or  at  least  one  of  its 
ingredients,  is  found  in  the  plant  in  increased  quantity. 

In  2,  chlorine,  but  not  sodium ;  in  3  and  4,  potash ;  in 
5,  sulphuric  acid  and  magnesia,  and  in  6,  lime,  are  present 
in  larger  proportion  than  in  the  ash  from  the  unmanured 
soil. 

6,  What  is  the  Normal  Composition  of  the  Ash  of  a 
Plant  ?  It  is  evident  from  the  foregoing  facts  and  consid 
erations  that  to  pronounce  upon  the  normal  composition 
of  the  ash  of  a  plant,  or,  in  other  words,  to  ascertain  what 
ash-ingredients  and  what  proportions  of  them  are  propei 
to  any  species  of  plant  or  to  any  of  its  parts,  is  a  matter 
of  much  difficulty  and  uncertainty. 

The  best  that  can  be  done  is  to  adopt  the  average  of  a 

great  number  of  trustworthy  analyses  as  the  approximate 

expression  of  ash-composition.     From  such  data,  however, 

?e  are  still  unable  to  decide  what  are  the  absolutely  es- 


164  HOW   CROPS    GROW. 

sential,  and  what  are  really  accidental  ingredients,  or  what 
amount  of  any  given  ingredient  is  essential,  and  to  what 
extent  it  is  accidental.  Wolff,  who  appears  to  have  first 
suggested  that  a  part  of  the  ash  of  plants  may  be  acci 
dental,  endeavored  to  approach  a  solution  of  this  question, 
by  comparing  together  the  ashes  of  samples  of  the  same 
plant,  cultivated  under  the  same  circumstances  in  all  re 
spects,  save  that  they  were  supplied  with  unequal  quantities 
of  readily  available  ash-ingredients.  The  analyses  of  the 
ashes  of  buckwheat-stems,  just  quoted,  belong  to  this  in 
vestigation.  Wolff  showed  that,  by  assuming  the  presence 
in  each  specimen  of  buckwheat-straw  of  a  certain  excess 
of  certain  ingredients,  and  deducting  the  same  from  the 
total  ash,  the  residuary  ingredients  closely  approximated 
in  their  proportions  to  those  observed  in  the  crop  which 
grew  in  an  unmanured  soil.  The  analyses  just  quoted, 
(p.  163,)  are  here  "corrected"  in  this  manner,  by  the  sub 
traction  of  a  certain  per  cent  of  those  ingredients  which 
in  each  case  were  furnished  to  the  plant  by  the  fertilizer 
applied  to  it.  The  numbers  of  the  analyses  correspond 
with  those  on  the  previous  page. 

123456 

20/J.  C.      20p.  C.  25^.  c.      8.5/?.  c.  IQ.Gp.c. 

Chloride  Carbonate  Carbonate  Sulphate  Carbonates 

After  deduction                        of           of  of             of  of  lime  and 

of Nothing .  potassium,  potash,  potash,    magnesia,  marjnesia. 

Potash 31.7           27.0           32.5  33.5           30.6  28.0 

Chloride  of  potassium.  7.4            9.1             1.0  3.9            7.4  11.3 

Chloride  of  sodium....  4.6            3.8            4.0  4.7            3.7  1.9 

Lime 15.7           17.3           16.0  14.5           15.3  14.6 

Magnesia 1.7            2.4            4.1  1.7            2.3  2.9 

Sulphuric  acid 4.7            3.5            3.4  5.4            2.1  4.1 

Phosphoric  acid 10.3           11.7            8.1  11.2           11.8  11.7 

Carbonic  acid 20.4           20.1           25.9  19.8           21.6  19.3 

Silica 3.6             5.2             5.2  5.3             5.2  6.1 

100.0    100.0    100.0    100.0    100  0    100.0 

The  correspondence  in  the  above  analyses  thus  "cor 
rected,"  already  tolerably  close,  might,  as  Wolff  remarks, 
(loc.  cit.)  be  made  much  more  exact  by  a  further  correc 
tion,  in  which  the  quantities  of  the  two  most  variable  in- 


THE    ASH    OF   PLANTS. 


gradients,  viz.  chlorine  and  sulphuric  aci^L-efiould  be  re 
duced  to  uniformity,  and  the  analyses  then  \>e  recalculated 
to  per  cent. 

In  the  first  place,  however,  we  are  not  w 
assuming  that  the  "  excess  "  of  chloride  of  potassT 
bonate  of  potash,  etc.,  deducted  in  the  above  analyse 
respectively,  was  all  accidental  and  unnecessary  to  the 
plant,  for,  under  the  influence  of  an  increased  amount  of  a 
nutritive  ingredient,  the  plant  may  not  only  mechanically 
contain  more,  but  may  chemically  employ  more  in  the 
vegetative  processes.     It  is  well  proved  that  vegetation 
grown  under  the  influence  of  large  supplies  of  nitrogenous 
manures,  contains  an  increased  proportion  of  nitrogen  in 
the  truly  assimilated  state  of  albumin,  gluten,  etc.     The 
Bame  may  be  equally  true  of  the  various  ash-ingredients. 

Again,  in  the  second  place,  we  cannot  say  that  in  any 
instance  the  minimum  quantity  of  any  ingredient  neces 
sary  to  the  vegetative  act  is  present,  and  no  more. 

It  must  be  remarked  that  these  great  variations  are  only 
seen  when  we  compare  together  plants  produced  on  poor 
soils,  i.  e.  on  those  which  are  relatively  deficient  in  some 
one  or  several  ingredients.  If  a  fertile  soil  had  been  em 
ployed  to  support  the  buckwheat  plants  in  these  trials,  we 
should  doubtless  have  had  a  very  different  result. 

In  1859,  Metzdorf,  ( WildcCs  CentralUatt,  1862,  2,  p. 
367,)  analysed  the  ashes  of  eight  samples  of  the  red-onion 
potato,  grown  on  the  same  field  in  Silesia,  but  differently 
manured. 

Without  copying  the  analyses,  we  may  state  some  of 
the  most  striking  results.  The  extreme  range  of  variation 
in  potash  was  5^  per  cent.  The  ash  containing  the  high 
est  percentage  of  potash  was  not,  however,  obtained  from 
potatoes  that  had  been  manured  with  50  pounds  of  this 
substance,  but  from  a  parcel  to  which  had  been  applied  a 
poudrette  containing  less  than  3  pounds  of  potash  for  the 
quantity  used. 


166  HOW   CROPS   GROW. 

The  unmanured  potatoes  were  relatively  the  richest  in 
lime,  phosphoric  acid,  and  sulphuric  acid,  although  several 
parcels  were  copiously  treated  with  manures  containing 
considerable  quantities  of  these  substances.  These  facts 
are  of  great  interest  in  reference  to  the  theory  of  the  action 
of  manures. 

7«  To  what  Extent  is  each  Ash-ingredient  Essential, 
and  how  far  may  it  be  Accidental?  Before  the  art  of 
chemical  analysis  had  arrived  at  much  perfection,  it  was 
believed  by  many  men  of  science,  that  the  ashes  of  the 
plant  were  either  unessential  to  growth,  or  else  were  the 
products  of  growth — were  generated  by  the  plant. 

Since  the  substances  found  in  ashes  are  universally  dis 
tributed  over  the  earth's  surface,  and  are  invariably  pres 
ent  in  all  soils,  it  is  not  possible  by  analysis  of  the  ash  of 
plants  growing  under  natural  conditions,  to  decide  whether 
any  or  several  of  their  ingredients  are  indispensable  to  veg 
etative  life.  For  this  purpose  it  is  necessary  to  institute 
experimental  inquiries,  and  these  have  been  prosecuted 
with  great  pains-taking,  though  not  with  results  that  are  hi 
all  respects  satisfactory. 

Experiments  in  Artificial  Soils, — The  Prince  Salm- 
Horstmar,  of  Germany,  has  been  a  most  laborious  student 
of  this  question.  His  plan  of  experiment  was  the  follow 
ing  :  the  seeds  of  a,  plant  were  sown  in  a  soil-like  medium, 
(sugar-charcoal,  pulverized  quartz,  purified  sand,)  which 
was  as  thoroughly  as  possible  freed  from  the  substance 
whose  special  influence  on  growth  was  the  subject  of  study. 
All  other  substances  presumably  necessary,  and  all  the 
usual  external  conditions  of  growth,  (light,  warmth, 
moisture,  etc.,)  were  supplied. 

The  results  of  195  trials  thus  made  with  oats,  wheat, 
barley,  and  col/a,  subjected  to  the  influence  of  a  great 
variety  of  artificial  mixtures,  have  been  described,  the 
most  important  of  which  will  shortly  be  given. 


THE    ASH    OF   PLANTS. 


1G7 


Experiments    in  Solutions,— Water-Culture,— Sachs, 

W.  Knop,  Stohmann,  ISTobbe,  Siegert,  and  others  have 
likewise  studied  this  subject.  Their  method  was  like  that 
of  Prince  Salm-Horstmar,  except  that  the  plants  were 
made  to  germinate  and  grow  independently  of  any  soil  j 
and,  throughout  the  experiment,  had  their  roots  immersed 
in  water,  containing  in  solution  or  suspension  the  sub 
stances  whose  action  was  to  be  observed. 

Water-  Culture  has  recently  contributed  so  much  to  our 
knowledge  of  the  conditions  of  vegetable  growth,  thai 
some  account  of  the  mode  of  conducting  it  may  be  proper^ 
iy  given    in    this    place.      Cause   a 
number  of  seeds  of  the  plant  it  is 
desired  to  experiment  upon  to  ger 
minate  in  moist  cotton  or  coarse  sand, 
and  when  the  roots  have  become  an 
inch   or    two   in    length,   select    the 
strongest  seedlings,  and  support  them, 
so  that  the  roots  shall  be  immersed  in 
water,  while  the  seeds  themselves  shall 
be  just  above  the  surface  of  the  liquid. 

For  this  purpose,  in  case  of  a  single 
maize  plant,  for  example,  provide  a 
quart  cylinder  or  bottle,  with  a  wide 
mouth,  to  which  a  cork  is  fitted,  as  in 
Fig.  22.  Cut  a  vertical  notch  in  the 
cork  to  its  center,  and  fix  therein  the 
stem  of  the  seedling  by  packing  with 
cotton.  The  cork  thus  serves  as  a 
support  of  the  plant.  Fill  the  jar 
with  pure  water  to  such  a  height 
that  when  the  cork  is  brought  to  its 
place,  the  seed,  8,  shall  be  a  little 
above  the  liquid.  If  the  endosperm 
or  cotyledons  dip  into  the  water,  they  will  speedily 
mould  and  rot;  they  require,  however,  to  bo  kept  in 


168  HOW   CROPS   GROW. 

a  moist  atmosphere.  Thus  arranged,  suitable  warmth^ 
ventilation,  and  illumination,  alone  are  requisite  to  con 
tinue  the  growth  until  tho  nutriment  of  the  seed  is  n early 
exhausted.  As  regards  illumination,  this  should  be  as  full 
as  possible,  for  the  foliage ;  but  the  roots  should  be  pro 
tected  from  it,  by  enclosing  the  vessel  in  a  shield  of  black 
paper,  as,  otherwise,  minute  parasitic  algaB  would  in  time 
develop  upon  the  roots,  and  disturb  their  functions.  For 
the  first  days  of  growth,  pure  distilled  water  may  advan 
tageously  surround  the  roots,  but  when  the  first  green  leaf 
appears,  they  should  be  placed  in  the  solution  whose  nu 
tritive  power  is  to  be  tested.  The  temperature  should  be 
properly  proportioned  to  the  light,  in  imitation  of  what  is 
observed  in  the  skillful  management  of  conservatory  or 
house-plants. 

The  experimenter  should  first  learn  how  to  produce 
large  and  well-developed  plants,  by  aid  of  an  appropriate 
liquid,  before  attempting  the  investigation  of  other  prob 
lems.  For  this  purpose,  a  solution  or  mixture  must  be 
prepared,  containing  in  proper  proportions  all  that  the 
plant  requires,  save  what  it  can  derive  from  the  atmos 
phere.  The  recent  experience  of  Nobbe  &  Siegert,  Wolff, 
and  others,  supplies  valuable  information  on  this  point. 
Prof.  Wolff  has  obtained  striking  results  with  a  variety  of 
plants  in  using  a  solution  made  essentially  as  follows : 

Place  20  grams,  (300  grains,)  of  the  fine  powder  of  well- 
burned  bones  with  a  half  pint  of  water  in  a  large  glass 
flask,  heat  to  boiling,  and  add  nitric  acid  cautiously  in 
quantity  just  sufficient  to  dissolve  the  bone-ash.  In  order 
to  remove  any  injurious  excess  of  nitric  acid,  pour  into  the 
hot  liquid,  solution  of  carbonate  of  potash  until  a  slight 
permanent  turbidity  is  produced;  then  add  11  grams,  (180 
grains,)  of  nitrate  of  potash,  7  grams,  (107  grains,)  of 
crystallized  sulphate  of  magnesia,  and  :)  grains,  (60  grains,) 
oi'  chloride  of  potassium,  with  water  enough  to  make  the 
solution  up  to  the  bulk  of  one  liter,  (or  quart.)  Mix  30 


THE   ASH    OP  PLANTS.  169 

cubic  cent.,  (one  fluid  ounce,)  of  this  liquid  with  a  liter, 
(or  quart,)  of  water  and  a  single  drop  of  strong  solution 
of  sulphate  of  iron,  and  employ  this  diluted  solution  to 
feed  the  plant. 

Wolff's  solution,  thus  prepared,  contained  in  1000  parts 
68  follows,  exclusive  of  iron : 

Phosphoric  acid  •-  •  8.234 
Lime  -  *  10.370 
Potash  -  ,  -  9.123 
Magnesia  -  -  -  -  1.403 
Sulphuric  acid  -  2.254 
Chlorine  -  -  0.885 
Nitric  acid  -  -  -  29.703 ^ 

Solid  Matters  -    '  61.972 

Water       -        -        -        -        -  938.028 


1000. 

This  solution  was  diluted  to  a  liquid  containing  but  one 
part  of  solid  matters  to  1000  or  2000  parts  of  water. 

The  solution  should  be  changed  every  week,  and  as  the 
plants  acquire  greater  size,  their  roots  should  be  trans 
ferred  to  a  larger  vessel,  filled  with  solution  of  the  same 
strength. 

It  is  important  that  the  water  which  escapes  from  the 
jar  by  evaporation  and  by  transpiration  through  the  plant, 
should  be  daily  or  oftener  replaced,  by  filling  it  with  pure 
water  up  to  the  original  level.  The  solution,  whose  prep 
aration  has  been  described,  may  be  turbid  from  the  sepa 
ration  of  a  little  white  sulphate  of  lime  before  the  last  dilu 
tion,  as  well  as  from  the  precipitation  of  phosphate  of  iron 
on  adding  sulphate  of  iron.  The  former  deposit  may  be 
dissolved,  though  this  is  not  needful;  the  latter  will  not 
dissolve,  and  should  be  occasionally  put  into  suspension  by 
stirring  the  liquid.  When  the  plant  is  half  grown,  further 
addition  of  iron  is  unnecessary. 

In  this  manner,  and  with  this  solution,  Wolff  produced 
8 


170  HOW    CROPS    GROW. 

a  maize  plant,  five  and  three  quarters  feet  high,  and  equal 
hi  every  respect,  as  regards  size,  to  plants  from  similar 
seed,  cultivated  in  the  field.  The  ears  were  not,  however, 
fully  developed  when  the  experiment  was  interrupted  by 
the  plant  becoming  unhealthy. 

With  the  oat  his  success  was  better.  Four  plants  were 
brought  to  maturity,  having  46  stems  and  1535  well-devel 
oped  seeds.  (  Vs.  St.,  VIII,  190-215.) 

In  similar  experiments,  Nobbe  obtained  buckwheat 
plants,  six  to  seven  feet  high,  bearing  three  hundred  plump 
and  perfect  seeds,  and  barley  stools  with  twenty  grain- 
bearing  stalks.  (  Vs.  St.,  VII,  7:2.) 

In  water-culture,  the  composition  of  the  solution  is  suf 
fering  continual  alteration,  from  the  fact  that  the  plant 
makes,  to  a  certain  extent,  a  selection  of  the  matters  pre 
sented  to  it,  and  does  not  necessarily  absorb  them  in  the 
proportions  in  which  they  originally  existed.  In  this  way, 
disturbances  arise  which  impede  or  become  fatal  to  growth. 
In  the  early  experiments  of  Sachs  and  Knop,  in  1860,  they 
frequently  observed  that  their  solutions  suddenly  acquired 
the  odor  of  sulphydric  acid,  and  black  sulphide  of  iron 
formed  upon  the  roots,  in  consequence  of  which  they  were 
shortly  destroyed.  This  reduction  of  a  sulphate  to  a  sul 
phide  takes  place  only  in  an  alkaline  liquid,  and  Stohmann 
was  the  first  to  notice  that  an  acid  liquid  might  be  made 
alkaline  by  the  action  of  liA'ing  roots.  The  plant,  in  fact, 
has  the  power  to  decompose  salts,  and  by  appropriat 
ing  the  acids  more  abundantly  than  the  bases,  the  Litter 
accumulate  in  the  solution  in  the  free  state,  or  as  carbon 
ates  with  alkaline  properties. 

To  prevent  the  reduction  of  sulphates,  the  solution  must 
be  kept  slightly  acid,  best  by  addition  of  a  very  little  free 
nitric  acid,  and  if  the  roots  blacken,  they  must  be  washed 
with  a  dilute  acid,  and,  after  rinsing  with  water,  must  be 
transferred  to  a  fresh  solution. 

On  the  other  hand,  Kiihn  has  shown  that  when  chloride 


THE   ASH    OF   PLANTS.  171 

of  ammonium  is  employed  to  supply  maize  with  nitrogen, 
this  salt  is  decomposed,  its  ammonia  assimilated,  and  its 
chlorine,  which  the  plant  cannot  use,  accumulates  in  the 
solution  in  the  form  of  chlorhydric  acid,  to  such  an  extent 
as  to  prove  fatal  to  the  plant,  (Henneberg's  Journal,  1864, 
pp.  116  and  135.)  Such  disturbances  are  avoided  by 
employing  large  volumes  of  solution,  and  by  frequently 
renewing  them. 

The  concentration  of  the  solution  of  is  by  no  means  a 
matter  of  indifference.  While  certain  aquatic  plants,  as 
sea-weeds,  are  naturally  adapted  to  strong  saline  solutions, 
agricultural  land-plants  rarely  succeed  well  in  water-cul 
ture,  when  the  liquid  contains  more  than  2 11000  of  solid  mat 
ters,  and  will  thrive  in  considerably  weaker  solutions. 

Simple  well-water  is  often  rich  enough  in  plant-food  to 
nourish  vegetation  perfectly,  provided  it  be  renewed  suf 
ficiently  often.  Sachs'  earliest  experiments  were  made  with 
well-water. 

Birner  and  Lucanus,  in  1864,  ( Vs.  St.,  VIII,  154,)  raised 
oat-plants  in  well-water,  which  in  respect  to  entire  weight 
were  more  than  half  as  heavy  as  plants  that  grew  simul 
taneously  in  garden  soil,  and,  as  regards  seed-production, 
fully  equalled  the  latter.  The  well-water  employed,  con 
tained  in  100.000  parts : 

Potash  2.10 

Lime  .-•**-        -        -      •  -      •    15.10 

Magnesia  -  -  .-•  -  ^  —  1.50 
Phosphoric  acid  -  •  -  -  0.16 
Sulphuric  acid  -  -  ^-v.  -  7.50 
Nitric  acid  -  -  6.00 

Silica,  Chlorine,  Oxide  of  iron  -     -  traces 

Solid  Matters      -  32.36 

Water     ...  -  -      99,967.64 

100,000 

Xobbe,  (  Vs.  St.,  YIH,  337,)  found  that  in  a  solution  con- 
taining  but  1 110000  of  solid  matters,  which  was  continually 


172  HOW   CROPS   GROW. 

renewed,  barley  made  no  progress  beyond  gei  urination,  and 
a  buckwheat  plant,  which  at  first  grew  rapidly,  was  soon 
arrested  in  its  development,  and  yielded  but  a  few  ripe 
seeds,  and  but  1.746  grm.  of  total  dry  matter. 

While  water-culture  does  not  provide  all  the  normal 
conditions  of  growth — the  soil  having  important  func 
tions  that  cannot  be  enacted  by  any  liquid  medium— it 
is  a  method  of  producing  highly-developed  plants,  under 
circumstances  which  admit  of  accurate  control  and  great 
variety  of  alteration,  and  is,  therefore,  of  the  utmost  value 
in  vegetable  physiology.  It  has  taught  important  facts 
which  no  other  means  of  study  could  reveal,  and  promises 
to  enrich  our  knowledge  in  a  still  more  eminent  degree. 

Potash,  Lime,  Magnesia,  Phosphoric  Acid,  and  Sul 
phuric  Acid,  are  absolutely  necessary  for  the  life  of 
Agricultural  Plants,  as  is  demonstrated  by  all  the  experi 
ments  hitherto  made  for  studying  their  influence. 

It  is  not  needful  to  recount  here  the  evidence  to  this 
effect  that  is  furnished  by  the  investigations  of  Salm- 
Horstmar,  Sachs,  Knop,  and  others.  (See,  especially, 
Birner  &  Lucanus,  Vs.  St.,  VIII,  128-161.) 

Is  Soda  Essential  for  Agricultural  Plants?  This 
question  has  occasioned  much  discussion.  A  glance  at 
the  table  of  ash-analyses,  (pp.  150-56,)  will  show  that  the 
range  of  variation  is  very  great  as  regards  this  alkali. 
Among  the  older  analysts,  Bichon  found  in  the  ash  of 
the  pea  13,  in  that  of  the  bean  19,  in  that  of  rye  19,  in  that 
of  wheat  27  per  cent  of  soda,  llerapath  found  15  per  cent 
of  this  substance  in  wheat-ash,  and  20  per  cent  in  ash  of 
rye.  Brewer  found  13  per  cent  in  the  ash  of  maize.  In  a 
few  other  analyses  of  the  grains,  we  find  similar  high  per 
centages.  In  most  of  the  analyses,  however,  soda  is  pres 
ent  in  much  smaller  quantity.  The  average  in  the  ashes 
of  the  grains  is  less  than  3  per  cent,  and  in  not  a  few  of 
the  analyses  it  is  entirely  wanting. 


THE    ASH    OF   PLANTS.  173 

In  the  older  analyses  of  other  classes  of  agricultural 
plants,  especially  in  root  crops,  similarly  great  variations 
occur. 

Some  uncertainty  exists  as  to  these  older  data,  for  the 
reason  that  the  estimation  of  soda  by  the  processes  custom 
arily  employed  is  liable  to  great  inaccuracy,  especially 
with  the  inexperienced  analyst.  On  the  one  hand,  it  is 
not  easy,  (or  has  not  been  easy  until  lately,)  to  detect, 
much  less  to  .estimate,  minute  traces  of  soda,  when  mixed 
with  much  potash  ;  while  on  the  other  hand,  soda,  if  pres 
ent  to  the  extent  of  a  per  cent  or  more,  is  very  liable  to 
be  estimated  too  high.  It  has  therefore  been  doubted  if 
these  high  percentages  in  the  ash  of  grains  are  correct. 

Again,  furthermore,  the  processes  formerly  employed  for 
preparing  the  ash  of  plants  for  analysis  were  such  as,  by 
too  elevated  and  prolonged  heating,  might  easily  occasion 
a  partial  or  total  expulsion  of  soda  from  a  material  which 
properly  should  contain  it,  and  we  may  hence  be  in  doubt 
whether  the  older  analyses,  in  which  soda  is  not  mention 
ed,  are  to  be  altogether  depended  upon. 

The  later  analyses,  especially  those  by  Bibra,  Zoeller, 
Arendt,  Bretschneider,  Ritthausen,  and  others,  who  have 
employed  well-selected  and  carefully-cleaned  materials  for 
their  investigations,  and  who  have  been  aware  of  all  the 
various  sources  of  error  incident  to  such  analyses,  must 
therefore  be  appealed  to  in  this  discussion.  From  these 
recent  analyses  we  are  led  to  precisely  the  same  conclusions 
as  were  warranted  by  the  older  investigations.  Here  fol 
lows  a  statement  of  the  range  of  percentages  of  soda  in  tho 
ash  of  several  field  crops,  according  to  the  newest  analyses  : 
Ash  of  Wheat  kernel,  none,  Bibra,  to  5°|0  Bibra. 


Potato  tuber,         none,  j  "       4°lo 


j  4.  7°|0  Ritthausen,     "  29.8°|0    Ritthausen. 
I  5.  7°|0  Bretschneider"  16.  GOJO    Bretschneidet 
Turnip  root,  7.7°[0  Anderson,       "  17.10|0    Anderson 


174  HOW  CROPS    GROW. 

Although,  as  just  indicated,  soda  has  been  found  want 
ing  in  the  wheat  kernel  and  in  potato  tubers,  in  some  in- 
Btances,  it  is  not  certain  that  it  was  absent  from  other 
parts  of  the  same  plants,  nor  has  it  been  proved,  so  far  ag 
we  know,  that  soda  is  wanting  in  any  entire  plant  which 
has  grown  on  a  natural  soil 

Weinhold  found  in  the  ash  of  the  stem  and  leaves  of  the 
common  live-for-ever,  (Sedum  telephium,}  no  trace  of  soda 
detectable  by  ordinary  means ;  while  in  the  ash  of  the 
roots  of  the  same  plant,  there  occurred  1.8  per  cent  of  this 
substance.  (  Vs.  St.,  IV,  p.  190.) 

It  is  possible,  then,  that,  in  the  above  instances,  soda 
really  existed  in  the  plants,  though  not  in  those  parts 
which  were  subjected  to  analysis.  It  should  be  added 
that  in  ordinary  analyses,  where  soda  is  stated  to  be  ab 
sent,  it  is  simply  implied  that  it  is  present  in  unweighable 
quantity,*  if  at  all,  while  in  reality  a  minute  amount  may 
be  present  in  all  such  cases.f 

The  grand  result  of  all  the  analytical  investigations 
hitherto  made,  with  regard  to  cultivated  agricultural 
plants,  then,  is  that  soda  is  an  extremely  variable  ingre 
dient  of  the  ash  of  plants,  and  though  generally  present 
in  some  proportion,  and  often  in  large  proportion,  has 
been  observed  to  be  absent  in  weighable  quantity  in  the 
seeds  of  grains  and  in  the  tubers  of  potatoes. 

Salm-Horstmar,  Stohmann,  Knop,  and  Nobbe  &  Sie- 
gert,  have  contributed  certain  synthetical  data  that  bear 
on  the  question  before  us. 

The  investigations  of  Salm-Horstmar  were  made  with 
the  greatest  nicety,  and  especial  attention  was  bestowed 
on  the  influence  of  very  minute  quantities  of  the  various 

*  Unweighable  quantities  are  designated  as  "  trace"  or  "traces." 
t  The  newly  discovered  methods  of  spectral  analysis,  by  which  -^^^^ 
of  a  grain  of  soda  may  be  detected,  have  demonstrated  that  this  element  10  so 
universally  distributed  that  it  is  next  to  impossible  to  find  or  make  anything  that 
is  free  from  it. 


THE    ASH    OF   PLANTS.  175 

substances  employed.  He  gives  as  the  result  of  numerous 
experiments,  that  for  wheat,  oats,  and  barley,  in  the  early 
vegetative  stages  of  growth,  soda,  while  advantageous, 
is  not  essential,  but  that  for  the  perfection  of  fruit  an  ap 
preciable  though  minute  quantity  of  this  substance  is  in* 
dispensable.  (  Versuche  und  Resultate  uber  die  JVahrung 
der  Pflanzen,  pp.  12,  27,  29,  36.) 

Stohmann's  single  experiment  led  to  the  similar  conclu 
sion,  that  maize  may  dispense  with  soda  in  the  earlier 
stages  of  its  growth,  but  requires  it  for  a  full  development, 
(Henneberg's  Jour,  far  .Landwirthschaft,  1862,  p.  25.) 

Knop,  on  the  other  hand,  succeeded  in  bringing  the 
maize  plant  to  full  perfection  of  parts,  if  not  of  size,  in  a 
solution  which  was  intended  and  asserted  to  contain  no 
soda.  ( Vs.  St.,  Ill,  p.  301.)  Nobbe  &  Siegert  came  to 
the  same  results  in  similar  trials  with  buckwheat.  (  Vs. 
St.,  IV,  p.  339.) 

The  experiments  of  Knop,  and  of  Nobbe  &  Siegert, 
while  they  prove  that  much  soda  is  not  needful  to  maize 
and  buckwheat,  do  not,  however,  satisfactorily  demon 
strate  that  a  trace  of  soda  is  not  necessary,  because  the 
solutions  in  which  the  roots  of  the  plants  were  immersed 
stood  for  months  in  glass  vessels,  and  could  scarcely 
fail  to  dissolve  some  soda  from  the  glass,  Ao-ain, 

O  vD  / 

slight  impurity  of  the  substances  which  were  employed  in 
making  the  solution    could  scarcely  be  avoided  without 
extraordinary  precautions,  and,  finally,  the  seeds  of  these 
plants   might  originally  have  contained    enough  soda  to 
supply  this  substance  to  the  plants  in  appreciable  quantity. 
To  sum  up,  it  appears  from  all  the  facts  before  us : 
1.  That  soda  is  never  totally  absent  from  plants,  but 
that, 

*2.  If  indispensable,  but  a  minute  amount  of  it  is  re 
quisite 

3.  That  the  foliage  and  succulent  portions  of  the  plant 


176  HOW   CROPS   GROW. 

may  include  a  considerable  amount  of  soda  that  is  not  nec 
essary  to  the  plant,  that  is,  in  other  words,  accidental.* 

Can  Soda  replace  Potash  ] — The  close  similarity  of  pot 
ash  and  soda,  and  the  variable  quantities  in  which  the 
latter  especially  is  met  with  in  plants,  has  led  to  the  as 
sumption  that  one  of  these  alkalies  can  take  the  place  of 
the  other. 

Salm-Horstmar,  and,  more  recently,  Knop  &  Schreber, 
have  demonstrated  that  soda  cannot  entirely  take  the  place 
of  potash — in  other  words,  potash  is  indispensable  to  plant 
life.  Cameron  concludes  from  a  series  of  experiments, 
which  it  is  unnecessary  to  describe,  that  soda  can  partially 
replace  potash.  A  partial  replacement  of  this  kind  would 
appear  to  be  indicated  by  many  facts. 

Thus,  Herapath  has  made  two  analyses  of  asparagus, 
one  of  the  wild,  the  other  of  the  cultivated  plant,  both 
gathered  in  flower.  The  former  was  rich  in  soda,  the  lat 
ter  almost  destitute  of  this  substance,  but  contained  cor 
respondingly  more  potash.  Two  analyses  of  the  ash  of 
the  beet,  one  by  Wolff,  (1.,)  the  other  by  Way,  (2.,)  ex 
hibit  similar  differences : 


Potash  

A  spa 
Wild. 
...18.8 

rag  us. 
Oultivated. 
50.5 
trace 
21.3 

8.3 
4.5 
12.4 
3.7 

Field 
1. 
57.0 
7.3 
5.8 
4.0 
4.9 
3.5 
12.9 
3.7 

Beet 
2. 
25.1 
34.1 
2.2 
2.1 
34.8 
3.6 
1.9 
1.7 

Soda  

...16.2 

...  28.1 

Magnesia  

....  1.5 

Chlorine  

....16.5 

Sulphuric  acid.  .  .   . 

....  9.2 

Phosphoric  acid 

,...12.8 

Silica.  .  . 

.  1.0 

These  results  go  to  show — it  being  assumed  that  only  a 
very  minute  amount  of  soda,  if  any,  is  absolutely  neces 
sary  to  plant-life — that  the  soda  which  appears  to  replace 
potash  is  accidental,  and  that  the  replaced  potash  is  acci- 


•  Soda  appears  to  be  essential  «,o  animal  life  .  since  all  the  food  of  animals  IB 
derived,  indirectly  at  least,  from  the  vegetable  kingdom,  it  is  a  wi*e  provision 
that  soda  is  contained  in,  if  it  be  not  indispensable  to  plants. 


THE    ASH    OF   PLANTS.  177 

dental  also,  or  in  excess  above  what  is  really  needed  by 
the  plant,  and  leaves  us  to  infer  that  the  quantity  of 
these  bodies  absorbed,  depends  to  some  extent  on  the  com 
position  of  the  soil,  and  is  to  the  same  degree  independent 
of  the  wants  of  vegetation. 

Alkalies  in  Strand  and  Marine  Plants, — The  above 
conclusions  cannot  as  yet  be  accepted  in  case  of  plants 
which  grow  only  near  or  in  salt  water.  Asparagus,  the 
beet  and  carrot,  though  native  to  saline  shores,  are  easily 
capable  of  inland  cultivation,  and  indeed  grow  wild  in 
total  or  comparative  absence  of  soda-compounds.* 

The  common  saltworts,  Salsola,  and  the  samphire,  Sali- 
comia,  are  plants,  which,  unlike  those  just  mentioned, 
never  stray  inland.  Gobel,  who  has  analyzed  these  plants 
as  occurring  on  the  Caspian  steppes,  found  in  the  soluble 
part  of  the  ash  of  the  Salsola  brachiata,  4.8  per  cent  of 
potash,  and  30.3  per  cent  of  soda,  and  in  the  Salicornia 
herbacea,  2.6  per  cent  of  potash  and  36.4  per  cent  of  soda; 
the  soda  constituting  in  the  first  instance  no  less  than  l\  16 
and  in  the  latter  !|24  of  the  entire  weight,  not  of  the  ash, 
but  of  the  air-dry  plant.  Potash  is  never  absent  in  these 
forms  of  vegetation.  (Agricultur-Chemie,  3te  Auf.,  p.  66.) 

According  to  Cadet,  (Liebig^s  Ernahrung  der  Veg.,  p. 
100,)  the  seeds  of  the  /Salsola  kali,  sown  in  common  garden 
soil,  gave  a  plant  which  contained  both  soda  and  potash ; 
from  the  seeds  of  this,  sown  also  in  garden  soil,  grew  plants 
in  which  only  potash-salts  with  traces  of  soda  could  be 
found. 

Another  class  of  plants — the  sea-weeds,  (algae,) — derive 
their  nutriment  exclusively  from  the  sea- water  in  which 
they  are  immersed.  Though  the  quantity  of  potash  in  sen- 
water  is  but  *  |ao  that  of  the  soda,  it  is  yet  a  fact,  as  showu 
by  the  analyses  of  Forchhammer,  (Tour  fur  Prdkt.  Chem.y 

*  This  is  not,  indeed,  proved  by  analysis,  in  case  of  the  carrot,  but  is  doubt 
less  true. 

8* 


178  HOW  CROPS  GROW. 

36,  p.  391,)  and  Anderson,  (Trans.  High,  and  Ag. 
1855-7,  p.  349,)  that  the  ash  of  sea-weeds  is,  in  general, 
as  rich,  or  even  richer,  in  potash  than  in  soda.  In  14 
analyses,  by  Forchhammer,  the  average  amount  of  Fodn 
in  the  dry  weed  was  3.1  per  cent;  that  of  potash  2.5  per 
cent.  In  Anderson's  results,  the  percentage  of  potash  i 
invariably  higher  than  that  of  soda.* 

Analogy  with  land-plants  would  lead  to  the  inference 
that  tho  soda  of  the  sea-weeds  is  in  a  great  degree  acci 
dental,  although,  necessarily,  special  investigations  are  re 
quired  to  establish  a  point  like  this, 

Oxide  of  Iron  is  essential  to  plants. — It  is  abundant 
ly  proved  that  a  minute  quantity  of  oxide  of  iron,  FeQ  O3, 
is  essential  to  growth,  though  the  agricultural  plant 
may  be  perfect  if  provided  with  so  little  as  to  be 
discoverable  in  its  ash  only  by  sensitive  tests.  Accord 
ing  to  Salm-Horstmar,  the  protoxide  of  iron  is  indispen 
sable  to  the  colza  plant.  ( Versuche,  etc.,  p.  35.)  Knop  as 
serts  that  maize,  which  refuses  to  grow  in  entire  absence 
of  oxide  of  iron,  flourishes  when  the  phosphate  of  iron, 
which  is  exceedingly  insoluble,  is  simply  suspended  in  the 
solution  that  bathes  its  roots  for  the  first  four  weeks  only 
of  the  growth  of  the  plant.  (Vs.  St.  V,p.  101.) 

We  find  that  the  quantity  of  oxide  of  iron  given  in  the 
analyses  of  the  ashes  of  agricultural  plants  is  small,  being 
usually  less  than  one  per  cent. 

Here,  too,  considerable  variations  are  observed.  In  the 
analyses  of  the  seeds  of  cereals,  oxide  of  iron  ranges  from 
an  unweighable  trace  to  2  and  even  3°|0.  In  root  crops  it 
has  been  found  as  high  as  5°|  0.  Kekule  found  in  the  ash 
of  gluten  from  wheat  7.1°|0  of  oxide  of  iron.  (Jahres 
bericht  der  Chem.,  1851,  p.  715.)  Schulz-Fleeth  found 
17.5°  |0  in  the  ash  of  the  albumin  from  the  juice  of  the 

*  Doubtless  dut  to  the  fact  that  the  material  used  by  Anderson  was  freed  bj 
washing  from  adhering  common  salt. 


THE    ASH    OF   PLANTS.  179 

potato  tuber.  The  proportion  of  ash  is,  however,  so  small 
that  in  case  of  potato-albumin,  the  oxide  of  iron  amounts 
to  but  0.12  per  cent  of  the  dry  substance.  (Der  Rationelle 
Ackerbau,  p.  82.) 

In  the  wood,  and  especially  in  the  bark  of  trees,  oxide 
of  iron  often  exists  to  the  extent  of  5-10°  |0.  The  largest 
percentages  have  been  found  in  aquatic  plants.  In  the  ash 
of  the  duck-meat,  (Lemna  trisulca,}  Liebig  found  7.4°  |0. 
Gorup-Besanez  found  in  the  ash  of  the  leaves  of  the  Trapa 
natatis  29.6°  |0,  and  in  the  ash  of  the  fruit-envelope  of  the 
same  plant  68.6°|0.  (Ann.  Ch.  Ph.,  118.  p.  223.) 

Probably  much  of  the  iron  of  agricultural  and  land 
plants  is  accidental.  In  case  of  the  Trapa  natans,  we 
cannot  suppose  all  the  oxide  of  iron  to  be  essential,  be 
cause  the  larger  share  of  it  exists  in  the  tissues  as  a  brown 
powder,  which  may  be  extracted  by  acids,  and  has  the  ap 
pearance  of  having  accumulated  there  mechanically. 

Doubtless  a  portion  of  the  oxide  of  iron  encountered  in 
analyses  of  agricultural  vegetation  has  never  once  existed 
within  the  vegetable  tissues,  but  comes  from  the  soil  which 
adheres  with  great  tenacity  to  all  parts  of  plants. 

Oxide  of  Manganese,  Mn3  04,  is  unessential  to  Agri 
cultural  Plants • — This  oxide  is  commonly  less  abundant 
than  oxide  of  iron,  and  is  often,  if  not  usually,  as  good  as 
wanting  in  agricultural  plants.  It  generally  accompanies 
oxide  of  iron  where  the  latter  occurs  in  considerable  quan 
tity.  Thus,  in  the  ash  of  Trapa,  it  was  found  to  the  extent 
of  7.5-14.7°|  0.  Sometimes  it  is  found  in  much  larger  quan 
tity  than  oxide  of  iron;  e.  g.,  C.  Frcsenius  found  11.2°|0 
of  oxide  of  manganese  in  ash  of  leaves  of  the  red  beech, 
(Fagus  sylvaticaj)  that  contained  but  1°  |0  of  oxide  of  iron, 
In  the  ash  of  oak  leaves,  ( Quercus  robur,)  Neubauer  found, 
of  the  former  6.6,  of  the  latter  but  1.2°  |0. 

In  ash  of  the  wood  of  the  larch,  (Larix  Europcea,} 
Bottinger  found  13.5° |n  Mn3  O4  and  4.2°|0  Fe,  Oa,  and  in 


180  HOW   CROPS   GROW. 

ash  of  wood  of  Pinus  sylvestris  18.2°  |0  Mn3  O4,  and  3.5' |. 
Fe2  O3.  In  ash  of  the  seed  of  colza,  Nitzsch  found  16.1°| 
Mn3  O4,  and  5.5  Fe3  O3.  In  case  of  land  plants,  these  high 
percentages  are  accidental,  and  specimens  of  rao^t  of  tho 
plants  just  named  have  been  analyzed,  which  were  free 
from  all  but  traces  of  oxide  of  manganese. 

Salm-Horstmar  concluded  from  his  experiments  that 
oxide  of  manganese  is  indispensable  to  vegetation.  Sachs, 
Knop,  and  most  other  experimenters  in  water-culture,  make 
no  mention  of  this  substance  in  the  mixtures,  which  in 
their  hands  have  served  for  the  more  or  less  perfect  devel 
opment  of  a  variety  of  agricultural  plants.  Birner  & 
Lucanus  have  demonstrated  that  manganese  is  not  needful 
to  the  oat-plant,  and  cannot  take  the  place  of  iron.  (  Vs. 
St.,  VIII,  p.  43.) 

Is  Chlorine  indispensable  to  Crops? — What  has 
been  written  of  the  occurrence  of  soda  in  plants  ap 
pears  to  apply  in  most  respects  equally  well  to  chlo 
rine.  In  nature,  soda,  or  rather  sodium,  is  generally 
associated  with  chlorine  as  common  salt.  It  is  most  prob 
ably  in  this  form  that  the  two  substances  usually  enter 
the  plant,  and  in  the  majority  of  cases,  when  one  of  them 
is  present  in  large  quantity,  the  other  exists  in  correspond 
ing  quantity.  Less  commonly,  the  chloi  me  of  plants  is  in 
combination  with  potassium  exclusively. 

Chlorine  is  doubtless  never  absent  froi  i  the  perfect  agri 
cultural  plant,  as  produced  under  natural  Conditions,  though 
its  quantity  is  liable  to  great  variation,  and  is  often  very 
small — so  small  as  to  be  overlooked,  except  by  the  careful 
analyst.  In  many  analyses  of  grain,  chlorine  is  not  men 
tioned.  Its  absence,  in  many  cases,  is  due,  without  doubt, 
to  the  fact  that  chlorine  is  readily  dissipated  from  the  ash 
of  substances  rich  in  phosphoric,  silicic,  or  sulphuric  acids, 
on  prolonged  exposure  to  a  high  temperature.  In  the 
later  analyses,  in  which  the  vegetable  substance,  instead 
of  being  at  once  burned  to  ashes,  at  a  high  red  heat,  is 


THE   ASH   OP   PLANTS.  1M 

first  charred  at  a  heat  of  low  redness,  and  then  leached 
with  water,  which  dissolves  the  chlorides,  and  separates 
them  from  the  unburned  carbon  and  other  matters,  chlo 
rine  is  invariably  mentioned.  In  the  tables  of  analyses, 
the  averages  of  chlorine  are  undeniably  too  low.  This  is 
especially  true  of  the  grains. 

The  average  of  chlorine  in  the  26  analyses  of  wheat  by 
Way  &  Ogston,  p.  150,  is  but  0.08°  |0,  it  not  being  found  at  all 
in  the  ash  of  21  samples.  In  Zoeller's  later  analyses,  chlorine 
is  found  in  every  instance,  and  averages  0.7°|0.  Weber's 
analysis,  as  compared  with  the  others,  would  indicate  a 
considerable  range  of  variability.  Weber  extracted  the 
charred  ash  with  water,  and  found  6°|0  of  chlorine,  which 
is  six  times  as  much  as  is  given  in  any  other  recorded  anal 
ysis  of  the  wheat  kernel.  This  result  is  in  all  probability 
erroneous. 

Like  soda,  chlorine  is  particularly  abundant  in  the  stems 
and  leaves  of  those  kinds  of  vegetation  which  grow  in  soils 
or  other  media  containing  much  common  salt.  It  accom 
panies  soda  in  strand  and  marine  plants,  and,  in  general, 
the  content  of  chlorine  of  any  plant  may  be  largely  in 
creased  or  diminished  by  supplying  it  to,  or  withholding 
it  from  the  roots. 

As  to  the  indispensableness  of  chlorine,  we  have  some 
what  conflicting  data.  Salm-Horstmar  concludes  that  a 
trace  of  it  is  needful  to  the  wheat  plant,  though  many  of 
his  experiments  in  reference  to  the  importance  of  this  ele 
ment  he  himself  regards  as  unsatisfactory.  Nobbe  & 
Siegert,  who  have  made  an  elaborate  investigation  on  the 
nutritive  relations  of  chlorine  to  buckwheat,  were  led  to 
conclude  that  while  the  stems  and  foliage  of  this  plant  are 
able  to  attain  a  considerable  development  in  the  absence 
of  chlorine,  (the  minute  amount  in  the  seed  itself  excepted,) 
presence  of  chlorine  is  essential  to  the  perfection  of  the 
kernel. 

On  the  other  hand,  Knop  excludes  chlorine  from  the 


182  HOW   CROPS   GROW. 

list  of  necessary  ingredients  of  maize,  and  from  not  yet 
fully  described  experiments  doubts  that  it  is  necessary  for 
buckwheat. 

Leydhecker,  in  a  more  recent  investigation,  has  come  to 
the  game  conclusions  as  Nobbe  &  Siegert,  regarding  the 
indispensableness  of  chlorine  to  the  perfection  of  buck 
wheat,  ( Vs.  St.,  VIII,  177.) 

From  a  series  of  experiments  in  water-culture,  Birner 
&  Lucanus,  ( Vs.  St.,  VIII,  160,)  conclude  that  chlorine 
is  not  indispensable  to  the  oat-plant,  and  has  no  specific 
effect  on  the  production  of  its  fruit.  Chloride  of  potassium 
increased  the  weight  of  the  crop,  chloride  of  sodium  gave 
a  larger  development  of  foliage  and  stem,  chloride  of  mag 
nesium  was  positively  deleterious,  under  the  conditions 
of  their  trials. 

Lucanus,  ( Vs.  St.,  VII,  363-71,)  raised  clover  by  wa 
ter-culture  without  chlorine,  the  crop,  (dry,)  weighing  in 
the  most  successful  experiments  240  times  as  much  as  the 
seed.  Addition  of  chlorine  gave  no  better  result. 

Nobbe,  (notes  to  above  paper,)  has  produced  normally 
developed  vetch  and  pea  plants,  but  only  in  solutions  con 
taining  chlorine.  Knop,  still  more  recently,  (Lehrbuch 
der  Agricultur-Ghemie,  p.  615,)  gives  his  reasons  for  not 
crediting  the  justness  of  the  conclusions  of  Nobbe  & 
Siegert  and  Leydhecker. 

Until  further  more  decisive  results  are  reached,  we  are 
warranted  in  adopting,  with  regard  to  chlorine  as  related 
to  agricultural  plants,  the  following  conclusions,  viz.: 

1.  Chlorine  is  never  totally  absent. 

2.  If  indispensable,  but  a  minute  amount  is  requisite  in 
case  of  the  cereals  and  clover. 

3.  Buckwheat,  vetches,  and  perhaps  peas,  require  a  not 
inconsiderable  amount  of  chlorine  for  full  development. 

4.  The  foliage  and  succulent  parts  may  include  a  con 
siderable  quantity  of  ch  orine  that  is  not  indispensable  to 
the  life  of  the  plant. 


THE    ASH    OF    PLANTS.  183 

Necessity  of  Chlorine  for  Strand  Plants,— A  single 
observation  of  Wiegmann  and  Polstorf,  (Preisschrift,) 
indicates  that  Salsola  kali  requires  chlorine,  though 
whether  it  be  united  to  potassium  or  sodium  is  indiffer 
ent.  These  experimenters  transplanted  young  salt-worts 
into  a  pot  of  garden  soil  which  contained  but  traces  of 
chlorine,  and  watered  them  with  a  weak  solution  of  chlo 
ride  of  potassium.  The  plants  grew  most  luxuriantly 
blossomed,  and  completely  filled  the  pot.  They  were 
then  put  out  into  the  earth,  without  receiving  further  ap 
plications  of  chlorine-compounds,  but  the  next  year  they 
became  unhealthy,  and  perished  at  the  time  of  blossoming. 

Silica  is  not  indispensable  to  Crops, — The  numerous 
analyses  we  now  possess  indicate  that  this  substance  is 
always  present  in  the  ash  of  all  parts  of  agricultural 
plants,  when  they  grow  in  natural  soils. 

In  the  ash  of  the  wood  of  trees,  it  usually  ranges  from 
1  to  3°|0,  but  is  often  found  to  the  extent  of  10-20°  |0, 
or  even  30°|  0,  especially  in  the  pine.  In  leaves,  it  is  usually 
more  abundant  than  in  stems.  The  ash  of  turnip-leaves 
contains  3-1 0°|  0 ;  of  tobacco-leaves,  5-18°  |0 ;  of  the  oat,  11- 
58°  |0.  (Arendt,  Norton.)  In  ash  of  lettuce,  20°  |0 ;  of  beech 
leaves,  26°|0;  in  those  of  oak,  31°  |0  have  been  observed. 
(Wicke,  Henmberg's  Jour.,  1862,  p.  156.) 

The  bark  or  cuticle  of  many  plants  contains  an  extraor 
dinary  amount  of  silica.  The  Cauto  tree,  of  South  America, 
(Hlrtella  silicea,)  is  most  remarkable  in  this  respect.  Its 
bark  is  very  firm  and  harsh,  and  is  difficult  to  cut,  haying  the 
texture  of  soft  sandstone.  In  Trinidad,  the  natives  mix 
its  ashes  with  clay  in  making  pottery.  The  bark  of  the 
Cauto  yields  34°  |0  of  ash,  and  of  this  96°  |0  is  silica.  (Wicke, 
Henneberg's  Jour.,  1862,  p.  143.) 

Another  plant,  remarkable  for  its  content  of  silica,  is  the 
bamboo.  The  ash  of  the  rind  contains  70°  |0,  and  in  the 
joints  of  the  stem  are  often  found  concretions  of  silica,  r& 
sembling  flint — the  so-called  2'abashir. 


184  HOW   CROPS    GROW. 

The  ash  of  the  common  scouring  rush,  (Equisetum 
male,)  has  been  found  to  contain  97.5°  |0  of  silica.  The 
straw  of  the  cereal  grains,  and  the  stems  and  leaves  of 
grasses,  both  belonging  to  the  botanical  family  Crraminece, 
are  specially  characterized  by  a  large  content  of  silica, 
ranging  from  40  to  70°  |0.  The  sedge  and  rush  families 
likewise  contain  much  of  this  substance. 

The  position  of  silica  in  the  plant  would  appear,  from 
the  percentages  above  quoted,  to  be,  in  general,  at  the  sur 
face.  Although  it  is  found  in  all  parts  of  the  plant,  yet 
the  cuticle  is  usually  richest,  and  this  is  especially  true  in 
cases  where  the  content  of  silica  is  large.  Davy,  in  1799, 
drew  attention  to  the  deposition  of  silica  in  the  cuticle,  and 
advanced  the  idea  that  it  serves  the  plant  an  office  of  sup 
port  similar  to  that  enacted  in  animals  by  the  bones. 

In  the  ash  of  the  pine,  (Pinus  sylvestrisj)  Wittstein  has 
obtained  results  which  indicate  that  the  age  of  wood  or 
bark  greatly  influences  the  content  of  silica.     He  found  in 
Wood  of  a  tree,  220  years  old,  32.5°|, 


Bark 


170 
135 
220 
170 
135 


24.1 

15.1,  and  in 

30.3 

14.4 

11.9 


In  the  ash  of  the  straw  of  the  oat,  Arendt  found  the  per 
centage  of  silica  to  increase  as  the  plant  approached  maturi 
ty.  So  the  leaves  of  forest  trees,  which  in  autumn  are  rich 
in  silica,  are  nearly  destitute  of  this  substance  in  spring 
time.  Silica  accumulates  then,  in  general,  in  the  older  and 
less  active  parts  of  the  plant,  whether  these  be  external  or 
internal,  and  is  relatively  deficient  in  the  younger  and 
really  growing  portions. 

This  rule  is  not  without  exceptions.  Thus,  the  chaff  of 
wheat,  rye,  and  oats,  is  richer  in  silica  than  any  other  part 
of  these  plants,  and  Bottinger  found  the  seeds  of  the  pine 
richer  in  silica  than  the  wood. 

In  numerous  instances,  silica  is  so  deposited  in  or  upon 


THE    ASH    OP   PLLNTS.  185 

the  cell-wall,  that  when  the  organic  matters  are  destroyed 
by  burning,  or  removed  by  solvents,  the  form  of  the  cell 
is  preserved  in  a  silicious  skeleton.  This  has  long  been 
known  in  case  of  the  Equisetums  and  Deutzias.  Here,  the 
roughnesses  of  the  stems  or  leaves  which  make  these  plant? 
useful  for  scouring,  are  fully  incrusted  or  interpenetrated 
by  silica,  and  the  ashes  of  the  cuticle  present  the  same  ap 
pearance  under  the  microscope  as  the  cuticle  itself. 

Lately,  Kindt,  Wicke,  and  Mohl,  have  observed  that  the 
hairs  of  nettles,  hemp,  hops,  and  other  rough-leaved  plants, 
are  highly  silicious. 

The  bark  of  the  beech  is  coated  with  silica — hence  the 
smooth  and  undecayed  surface  which  its  trunk  presents. 
The  best  textile  materials,  which  are  bast-fibers  of  various 
plants,  viz.,  common  hemp,  manilla-hemp,  (Masa  textilis,) 
aloe-hemp,  (Agave  Americana,)  common  flax,  and  New 
Zealand  flax,  (P/iormium  tenax,}  are  completely  incrusted 
with  silica.  In  jute,  (Corchorus  textilis,)  some  cells  are 
partially  incrusted.  The  cotton  fiber  is  free  from  silica. 
Wicke,  (loc.  cit.,)  suggests  that  the  durability  of  textile 
fibers  is  to  a  degree  dependent  on  their  content  of  silica. 

The  great  variableness  observed  in  the  same  plant,  and 
in  the  same  part  of  the  plant,  as  to  the  content  of  silica, 
would  indicate  that  this  substance  is  at  least  in  some  de 
gree  accidental. 

In  the  ashes  of  ten  kinds  of  tobacco  leaves,  Fresenius 
&  Will  found  silica  to  range  from  5.1  to  18.4  per  cent. 
The  analysis  of  the  ash  of  13  samples  of  pea-straw,  grown 
on  different  soils  from  the  same  seed  during  the  same  year, 
under  direction  of  the  ';  Landes  Oeconomie  Collegium,"  of 
Prussia,  gave  the  following  percentages  of  silica,  viz,: 
0.56;  0.75;  2.30;  2.32;  2.80;  3.29;  3.57;  5.15;  5.82; 
8.03 ;  8.32 ;  9.77 ;  21.35.  Analyses  of  the  ash  of  9  samples 
of  colza-straw,  all  produced  from  the  same  seed  on  differ* 
ent  soils,  gave  the  following  percentages :  1.00 ;  1.14 ;  3.02 ; 
3.57 ;  4.65 ;  5  08 ;  7.81 ;  11.88 ;  17.12.  (Journal  farprakt. 


186  HOW   CROPS   GKOW. 

Chem.,  xlviii,  474-7.)  Such  instances  might  be  greatly 
multiplied. 

The  idea  that  a  part  of  the  silica  is  accidental  is  further 
sustained  by  the  fact  observed  by  Saussure,  the  earliest  in 
vestigator  of  the  composition  of  the  ash  of  plants,  (Re- 
pherches  sur  la  Vegetation,  p.  28:2,)  that  crops  raised  on  a 
iilicious  soil  are  in  general  richer  in  silica  than  those  grown 
on  a  calcareous  soil.  Norton  found  in  the  ash  of  the  chaff 
of  the  Hopeton  oat  from  a  light  loam  56.7  per  cent,  from 
a  poor  peat  soil  50.0  of  silica,  while  the  chaff  of  the  potato- 
oat  from  a  sandy  soil  gave  70.9  per  cent. 

Salin-Horstmar  obtained  some  remarkable  results  in  the 
course  of  his  synthetical  experiments  on  the  mineral  food 
of  plants,  which  fully  confirmed  him  in  the  opinion  that 
silica  is  indispensable  to  vegetation.  He  found  that  an 
oat  plant,  having  for  its  soil  pure  quartz,  (insoluble  silica,) 
witli  addition  of  the  elements  of  growth,  soluble  silica  ex- 
cepted,  not  only  grew  well,  but  contained  in  its  ash  23°  |, 
of  silica,  or  as  great  a  proportion  as  exists  in  the  plant 
raised  under  normal  conditions.  This  silica  may,  however, 
have  been  mostly  derived  from  the  husk  of  the  seed,  for 
the  plant  was  a  very  small  one. 

Sachs,  in  1862,  was  the  first  to  publish  evidence  indi 
cating  strongly  that  silica  is  not  a  necessary  ingredient  of 
maize.  He  obtained  in  his  early  essays  in  water-culture  a 
maize  plant  of  considerable  development,  whose  ashes  con* 
tained  but  0.7°  |0  of  silica.  Shortly  afterwards,  Knop  pro 
duced  a  maize  plant  with  140  ripe  seeds,  and  a  dry-weight 
of  50  grammes,  (nearly  2  oz.  av.,)  in  a  medium  so  free  from 
silica  that  a  mere  trace  of  this  substance  could  be  found  in 
the  root,  but  half  a  milligramme  in  the  stem,  and  22  milli 
grammes  in  the  15  leaves  and  sheaths.  It  was  altogether 
absent  from  the  seeds.  The  ash  of  the  leaves  of  this  plant 
thus  contained  but  0.54  per  cent  of  silica,  and  the  stem 
but  0.07  per  cent.  Way  &  Ogston  found  in  the  ash  of 
maize,  leaf  and  stem  together,  27.98  per  cent  of  silica. 


THE    ASH    OF    PLANTS.  187 

Knop  inclined  to  believe  that  the  little  silica  he  found 
in  his  maize  plant  was  due  to  dust,  and  did  not  belong  to 
the  tissues  of  the  plant.  He  remarked,  "  I  believe  that 
silica  is  not  to  be  classed  among  the  nutritive  elements  of 
the  Gramineae,  since  I  have  made  similar  observations  in 
the  analysis  of  the  ashes  of  barley." 

In  the  numerous  experiments  that  have  been  made  more 
recently  upon  the  growth  of  plnnts  in  aqueous  solutions, 
by  Sachs,  Knop,  Nobbe  &  Siege rt,  Stohmann,  Rauten- 
berg  &  Kiihn,  Birner  &  Lucanus,  Leydhecker,  Wolff, 
and  Hampe,  silica,  in  nearly  all  cases,  has  been  excluded,  so 
far  as  it  is  possible  to  do  so  in  the  use  of  glass  vessels. 
This  has  been  done  without  prejudice  to  the  development 
of  the  plants.  Nobbe  &  Siegert  and  Wolff  especiall} 
have  succeeded  in  producing  buckwheat,  maize,  and  the 
oat,  in  full  perfection  of  size  and  parts,  with  this  exclusion 
of  silica. 

Wolff,  ( Vs.  St.,  VIII,  p.  200,)  obtained  ii  the  ash  of 
maize  thus  cultivated,  2— 3°|0  of  silica,  Avhile  the  same  two 
varieties  from  the  field  contained  in  their  ash  11^— 13°|0. 
The  proportion  of  ash  was  essentially  the  same  in  both 
cases,  viz.,  about  6°|0.  Wolff's  results  with  the  oat  plant 
were  entirely  similar.  Birner  &  Lucanus,  ( Vs.  St.,  VIII, 
141,)  found  that  the  supply  of  soluble  silicates  to  the  oat 
made  its  ash  very  rich  in  silica,  (40°  |0,)  but  diminished  the 
growth  of  straw,  without  affecting  that  of  the  seed,  as 
compared  with  plants  nearly  destitute  of  silica. 

While  it  is  not  thus  demonstrated  that  utter  absence  of 
silica  is  no  hindrance  to  the  growth  of  plants  which  are 
ordinarily  rich  in  this  substance,  it  is  certain  that  very 
little  will  suffice  their  needs,  and  highly  probable  that  it 
is  in  no  way  essential  to  their  physiological  development. 

The  Ash-Ingredients,  which  are  indispensable  to  Crops, 
may  be  taken  up  in  larger  quantity  than  is  essential ,~ 

More  than  sixty  years  ago,  Saussure  described  a  simple 


188  HOW    CROPS    GUOW. 

experiment  which  is  conclusive  on  this  point.  He  gathered 
a  number  of  peppermint  plants,  and  in  some  determined 
the  amount  of  dry-matter,  which  was  40.3  per  cent.  The 
roots  of  others  were  then  immersed  in  pure  water,  and  tne 
plants  were  allowed  to  vegetate  2£  months  in  a  place  ex 
posed  to  air  and  light,  but  sheltered  from  rain. 

At  the  termination  of  the  experiment,  the  plants,  which 
originally  weighed  100,  had  increased  to  216  parts,  and 
the  dry  matter  of  these  plants,  which  at  first  was  40.3,  had 
become  62  parts.  The  plants  could  have  acquired  from 
the  glass  vessels  and  pure  water  no  considerable  quantity  of 
mineral  matters.  It  is  plain,  then,  that  the  ash-ingredients 
which  were  contained  in  two  parts  of  the  peppermint  were 
sufficient  for  the  production  and  existence  of  three  parts. 
We  may  assume,  therefore,  that  at  least  one-third  of  the 
ash  of  the  original  plants  was  in  excess,  and  accidental. 

The  fact  of  excessive  absorption  of  essential  ash-in 
gredients  is  also  demonstrated  by. the  precise  experiments 
of  Wolff  on  buckwheat,  already  described,  (see  p.  164,) 
where  the  point  in  question  is  incidentally  alluded  to,  and 
the  difficulties  of  deciding  how  much  excess  may  occur, 
are  brought  to  notice.  (See  also  pp.  176  and  179  in  regard 
to  potash  and  oxide  of  iron.) 

As  a  further  striking  instance  of  the  influence  of  the 
nourishing  medium  on  the  quantity  of  ash-ingredients  in 
the  plant,  the  following  is  adduced,  which  may  serve  to 
put  in  still  stronger  light  the  fact  that  a  plant  does  not 
always  require  what  it  contains. 

Nobbe  &  Siegert  have  made  a  comparative  study  of 
the  composition  of  buckwheat,  grown  on  the  one  hand  in 
garden  soil,  and  on  the  other  in  an  aqueous  solution  of 
saline  matters.  (The  solution  contained  sulphate  of  mag 
nesia,  chloride  of  calcium,  phosphate  and  nitrate  of  potash, 
with  phosphate  of  iron,  which  together  constituted  0.316°  | 
of  the  liquid.)  The  ash-percentage  was  much  higher  m 


THE    ASH    OF   PLANTS.  180 

tfcs  water-plants  than  in  the  garden-plants,  as  shown  by  the 
subjoined  figures.    (Vs.  St.,  V,  p.  132.) 

Per  cent  of  ash  in 

Stems  and  Leaves.      Hoots.  Seeds.  Entire  Plant. 

Water-plant 18.6       *          15.3  2.6  16.7 

Garden-plant....  8.7  6.8  2.4  7.1 

We  have  seen  that  well-developed  plants  contain  a 
larger  proportion  of  ash  than  feeble  ones,  when  they  grow 
side  by  side  in  the  same  medium.  In  disregard  of  this 
general  rule,  the  water-plant  in  the  present  instance  has 
an  ash-percentage  double  that  of  the  land-plant,  although 
the  former  was  a  dwarf  compared  with  the  latter,  yielding 
but  '|6  as  much  dry  matter.  The  seeds,  however,  are 
scarcely  different  in  composition. 

Disposition  by  the  Plant  of  excessive  or  superfluous 
ash-ingredients. — The  ash-ingredients  taken  up  by  a  plant 
in  excess  beyond  its  actual  wants  may  be  disposed  of  in 
three  ways.  The  soluble  matters — those  soluble  by  them 
selves,  and  also  incapable  of  forming  insoluble  combina 
tions  with  other  ingredients  of  the  plant — viz.,  the  alkali 
chlorides,  sulphates,  carbonates,  and  phosphates,  the 
chlorides  of  calcium  and  magnesium,  may — 

1*9  Remain  dissolved  in,  and  diffused  throughout,  the 
juices  of  the  plant ;  or, 

2.)  May  exude  upon  the  surface  as  an  efflorescence,  and 
be  washed  off  by  rains. 

Exudation  to  the  surface  has  been  repeatedly  observed 
in  case  of  cucumbers  and  other  kitchen  vegetables,  grow 
ing  in  the  garden,  as  well  as  with  buckwheat  and  barley 
in  water-culture.  (  Vs.  St.,  VI,  p.  37.) 

Saussure  found  in  the  white  incrustations  upon  cucum 
ber  leaves,  besides  an  organic  body  insoluble  in  water 
and  alcohol,  chloride  of  calcium,  with  a  trace  of  chlo 
ride  of  magnesium.  The  organic  substance  so  enveloped 
the  chloride  of  calcium  as  to  prevent  deliquescence  of 
the  latter.  (Recherches  sur  la  Veg.,  p.  265.) 


190  now  CROPS  GROW. 

Saussure  proved  that  foliage  readily  yields  up  saline 
matters  to  water.  lie  placed  hazel  leaves  eight  successive 
times  in  renewed  portions  of  pure  water,  leaving  them 
therein  15  minutes  each  time,  and  found  that  by  this  treat 
ment  they  lost  J|16  of  their  ash-ingredients.  The  por 
tion  thus  dissolved  was  chiefly  alkaline  salts;  but  con« 
sisted  in  part  of  earthy  phosphates,  silica,  and  oxide  of 
iron.  (Recherehes,  p.  287.) 

Ritthausen  has  shown  that  clover  which  lies  exposed  to 
rain  after  being  cut,  may  lose  by  washing  more  than  *| . 
of  its  ash-ingredients. 

Mulder,  ( Ghemie  der  Ackerkrume,  II,  p.  305,)  attributes 
to  loss  by  rain  a  considerable  share  of  the  variations  in  per 
centage  and  composition  of  the  fixed  ingredients  of  plants. 
We  must  not,  however,  forget  that  all  the  experiments 
which  indicate  great  loss  in  this  way,  have  been  made  on 
the  cut  plant,  and  their  results  may  not  hold  good  to  the 
same  extent  for  uninjured  vegetation,  which  certainly  does 
not  admit  of  soaking  in  water.  Further  investigations 
must  decide  this  point. 

3.  The  insoluble  matters,  or  those  which  become  insolu 
ble  in  the  plant,  viz.,  the  sulphate  of  lime,  the  oxalates,  phos 
phates,  and  carbonates  of  lime  and  magnesia,  the  oxides  of 
iron  and  manganese,  and  silica,  may  be  deposited  as  crys 
tals  or  concretions  in  the  cells,  or  may  incrust  the  cell- 
walls,  and  thus  be  set  aside  from  the  sphere  of  vital 
action. 

In  the  denser  and  comparatively  juiceless  tissues,  as  in 
bark,  old  wood,  and  ripe  seeds,  we  find  little  variation  in 
the  content  of  soluble  matters.  These  are  present  in  large 
and  variable  quantity  only  in  the  succulent  organs. 

In  bark,  (cuticle,)  wood  and  seed  envelopes,  (husks, 
shells,  chaff,)  we  often  find  silica,  the  oxides  of  iron  and 
manganese,  and  carbonate  of  lime — all  insoluble  substances 
— accumulated  in  considerable  amount.  In  bran — the 
cuticle  of  the  kernels  of  cereals- -phosphate  of  magnesia 


THE    ASH    OF   PLANTS. 


F!F% 

O          19, 

\ 

exists  in  comparatively  large  quantity.  In  thexlense  teak 
wood,  concretions  of  phosphate  of  lime  have  been  noticed. 
Of  a  certain  species  of  cactus,  ( Cactus  senilis,}  80^  of 
the  dry  matter  consists  of  crystals,  probably  a  lime  salt/^C' 

That  the  quantity  of  matters  thus  segregated  is  in  some 
degree  proportionate  to  the  excess  of  them  in  the  nourish 
ing  medium  in  which  the  plant  grows  has  been  observ 
ed  by  Nobbe  &  Siegert,  who  remark  that  the  two  por 
tions  of  buckwheat,  cultivated  by  them  in  solutions  and 
in  garden  soil  respectively,  (p.  188,)  both  contained  crys 
tals  and  globular  crystalline  masses,  consisting  probably 
of  oxalates  and  phosphates  of  lime  and  magnesia,  depos 
ited  in  the  rind  and  pith;  but  that  these  were  by  far  most 
abundant  in  the  water-plants^  whose  ash-percentage  was 
twice  as  great  as  that  of  the  land-plants. 

These  insoluble  substances  may  either  be  entirely  unes 
sential,  as  appears  to  be  the  case  with  silica,  or,  having 
once  served  the  wants  of  the  plant,  may  be  rejected  as  no 
longer  useful,  and  by  assuming  the  insoluble  form,  are  re 
moved  from  the  sphere  of  vital  action,  and  become  as  good 
as  dead  matter.  They  are,  in  fact,  excreted,  though  not, 
in  general,  formally  expelled  be 
yond  the  limits  of  the  plant.  They 
are,  to  some  extent,  thrown  off  into 
the  bark,  or  into  the  older  wood 
or  pith,  or  else  are  virtually  en 
cysted  in  the  living  cells. 

The  occurrence  of  crystallized 
salts  thus  segregated  in  the  cells 
of  plants  is  illustrated  by  the 
following  cuts.  Fig.  23  represents 
a  crystallized  concretion  ot'oxalate 

of  lime,  having  a  basis  or  skeleton  of  cellulose,  from  a  leaf 
of  the  walnut.  (Payen,  Chhnie  Industrielle  PL  XII.)  Fig. 
24  is  a  mass  of  crystals  of  a  lime  salt,  from  the  leaf  stem 
of  rhubarb.  Fig.  25,  similar  crystals  from  the  beet  root. 


192 


HOW    CROPS    GROW. 


In  the  root  of  the  young  bean,  Sachs  found  a  ring  of  cells, 
containing  crystals  of  sulphate  of  lime.     (Sitzungsberichte 

der  Wien.  Akacl,  37,  p.  106.) 
Bailey  observed  in  certain 
parts  of  the  inner  bark  of  the 
locust  a  series  of  cells,  each 
of  which  contained  a  crystal. 
In  the  onion-bulb,  and  many 
Fig.  24.  Fig.  25.  ot]ier  plants,  crystals  are 

abundant.     ( Gray's  Struct.  Botany,  5th  Ed.,  p.  59.) 

Instances  are  not  wanting  in  which  there  is  an  obvious 
excretion  of  mineral  matters,  or  at  least  a  throwing  of 
them  off  to  the  surface.  Silica,  as  we  have  see1.),  is  often 
found  in  the  cuticle,  but  it  is  usually  imbedded  in  the  cell- 
wall.  In  certain  plants,  other  substances  accumulate  in 
considerable  quantity  without  the  cuticle.  A  striking  ex 
ample  is  furnished  by  Saxifraga  crustata,  a  low  European 
plant,  which  is  found  in  lime  soils. 
The  leaves  of  this  saxifrage  are 
entirely  coated  with  a  scaly  in 
crustation  of  carbonate  of  lime 
and  carbonate  of  magnesia.  At 
the  edges  of  the  leaf,  this  incrusta 
tion  acquires  a  considerable  thick 
ness,  as  is  illustrated  by  figure  26, 
a.  In  an  analysis  made  by  linger, 
to  whom  these  facts  are  due,  the 
fresh,  (undried,)  leaves  yielded  to 
a  dilute  acid  4.14°  |0  of  carbonate 
of  lime,  and  0.82°  |0  of  carbonate 
of  magnesia. 

linger  learned  by  microscopic 
investigation  that  this  excretion  of  carbonates  proceeds 
mostly  from  a  series  of  glandular  expansions  at  the  margin 
of  the  leaf,  which  are  directly  connected  with  the  sap-ducts 
of  the  plant.  (Sitz'berichte  der  Wien.  Akad.,  43,  p.  519.) 


THE   ASH    OF   PLANTS.  193 

In  figure  26,  a  represents  the  appearance  of  a  leaf,  magnified  4)^  diam« 
eteis.  Around  the  borders  are  seen  the  scales  of  carbonate  of  lime  ; 
some  of  these  have  been  detached,  leaving  round  pits  on  the  surface  of 
the  leaf:  c,  d,  exhibit  the  scales  themselves,  e  in  profile :  b  shows  a  leaf, 
freed  from  its  incrustation  by  an  acid,  and  from  its  cuticle  by  potash- 
solution,  so  as  to  exhibit  the  veins,  (ducts,)  and  glands,  whose  course 
the  carbonate  of  lime  chiefly  takes  in  its  passage  through  the  plant. 

Further  as  to  the  state  of  ash-ingredients, — It  is  by  no 

means  true  that  the  ash-ingredients  always  exist  in  plants 
in  the  forms  under  which  they  are  otherwise  familiar 
to  us. 

Arendt  and  Hellriegel  have  studied  the  proportions  of 
soluble  and  insoluble  matters,  the  former  in  the  ripe  oat 
plant,  and  the  latter  in  clover  at  various  stages  of  growth. 

Arendt  extracted  from  the  leaves  and  stems  of  the  oat- 
plant,  after  thorough  grinding,  the  whole  of  the  soluble 
matters  by  repeated  washings  with  water.*  He  found  that 
all  the  sulphuric  acid  and  all  the  chlorine  were  soluble. 
Nearly  all  the  phosphoric  acid  was  removed  by  water.  The 
larger  share  of  the  lime,  magnesia,  soda,  and  potash,  was 
soluble,  though  a  portion  of  each  escaped  solution.  Oxide 
of  iron  was  found  ill  both  the  soluble  and  insoluble  state. 
In  the  leaves,  iron  was  found  among  the  insoluble  matters 
after  all  phosphoric  acid  had  been  removed.  Finally,  silica 
was  mostly  insoluble,  though  in  all  cases  a  small  quantity 
occurred  in  the  soluble  condition,  viz.,  3-8  parts  in  10,000 
of  the  dry  plant.  (Wachsthum  der  TIaferpflanze,  pp.  168, 
183-4.  See,  also,  table  on  p.  198.) 

Weiss  and  Wiesner  have  found  by  microchemical  investi 
gation  that  iron  exists  as  insoluble  compounds  of  protox 
ide  and  sesquioxide,  both  in  the  cell-membrane  and  in  the 
cell-contents.  (Sitdberichte  der  Wiener  Akad.,  40,  278.) 

Hellriegel  found  that  a  larger  proportion  of  the  various 
bases  was  soluble  in  young  clover  than  in  the  mature 
plant.  As  a  rule,  the  leaves  gave  most  soluble  matters, 

*  To  extract  the  soluble  parts  of  the  grain  in  this  way  wan  impossible. 

9 


J94  HOW    CROPS    GROW. 

the  leaf-stalks  less,  and  the  stems  least.     He  obtained, 
among  others,  the  following  results.     (  Vs.  St.,  IV,  p.  59,) 
Of  100  parts  of  the  following  fixed  ingredients  of  clover, 
were  dissolved  in  the  sap,  and  not  dissolved — 

In  younq  leaves.  In  full-grown  kavet. 

Poti*lr  i  dissolved 75.2  37.3 

{undissolved 24.8  63.7 


Lime 


(dissolved 69.5  73.4 


1  undissolved 30.5  27.6 

Mncrr  P«ii       ]  dissolved 43.6  78.3 

Magnesia       -j  undissoived 50.4  21.7 

Phosphoric    (  dissolved 20.9  19.9 

acid         1  undissolved 79.1  80.1 

dissolved 2G.8  16.1 


Silica 


undissolved 73.2  83.9 


These  researches  demonstrate  that  potash  and  soda — 
bodies,  all  of  whose  commonly  occurring  compounds,  sili 
cates  excepted,  are  readily  soluble  in  water — enter  into 
insoluble  combinations  in  the  plant ;  while  phosphoric  acM, 
which  forms  insoluble  salts  with  lime,  magnesia,  and  iron, 
is  freely  soluble  in  connexion  with  these  bases  in  tho  sap. 

It  should  be  added  that  sulphates  may  be  absent  from 
the  plant  or  some  parts  of  it,  although  they  are  found  in 
the  ashes.  Thus  Arendt  discovered  no  sulphates  in  the 
lower  joints  of  the  stem  of  oats  after  blossom,  though  in 
the  upper  leaves,  at  the  same  period,  sulphuric  acid,  (S  O3,) 
formed  nearly  7°|0  of  the  sum  of  the  fixed  ingredients. 
(Wachsthum  der  Haferpf.,  p.  157.)  Ulbricht  found  that 
sulphates  were  totally  absent  from  the  lower  leaves  and 
stems  of  red  clover,  at  a  time  when  they  were  present 
in  the  upper  leaves  and  blossom.  (  Vs.  St.,  IV,  p.  oO,  7h- 
bette.)  Both  Arendt  and  Ulbricht  observed  that  sulphur 
existed  in  all  parts  of  the  plants  they  experimented  upon ; 
in  the  parts  just  specified,  it  was,  however,  no  longer  com 
bined  to  oxygen,  but  had,  doubtless,  become  an  integral 
part  of  some  albuminoid  or  other  complex  organic  body. 
Thus  the  oat  stem,  at  the  period  above  cited,  contained  ,°, 
quantity  of  sulphur,  which,  had  it  been  converted  into 
sulphuric  acid,  would  have  amounted  to  14°  |0  of  the  fixed 


THE   ASH    OF   PLANTS.  195 

ingredients.  In  the  clover  leaf,  at  a  time  when  it  was 
totally  destitute  of  sulphates,  there  existed  an  amount  of 
sulphur,  which,  in  the  form  of  sulphuric  acid,  would  have 
made  13,70|0  of  the  fixed  ingredients,  or  one  per  cent  of 
the  dry  leaf  itself.* 

Other  ash-ingredients. — S;ilm-Horstmar  has  described 
gome  experiments,  from  which  he  infers  that  a  minute 
amount  of  Lithia  and  Fluorine,  (the  latter  as  fluoride  of 
potassium,)  are  indispensable  to  the  fruiting  of  barley. 
(Jour,  fur  prakt.  Chem.,  84,  p.  140.)  The  same  observer, 
some  years  ago,  was  led  to  conclude  that  a  trace  of  Titanic- 
acid  is  a  necessary  ingredient  of  plants.  The  later  results 
of  water-culture  would  appear  to  demonstrate  that  these 
conclusions  are  erroneous. 

It  is,  however,  possible,  as  Mulder  has  suggested,  (  Che 
mie  der  Ackerkmme,  II,  341,)  that  the  failure  of  certain 
crops,  after  long-continued  cultivation  in  the  same  soil, 
may  be  due  to  the  exhaustion  of  some  of  these  less  abun 
dant  and  usually  overlooked  substances.  Land  not  unfre- 
quently  becomes  "clover-sick,"  i.  e.,  refuses  to  produce 
good  crops  of  clover,  even  with  the  most  copious  manur- 
ings.  In  Vaucluse,  according  to  Mulder,  the  madder  crop 
has  suffered  a  deterioration  in  quality — the  coloring  effect 
of  the  root  having  diminished  one-fourth — as  an  apparent 
result  of  long  cultivation  on  the  same  soil,  although  the 
seed  is  annually  renewed  from  Asia  Minor,  and  great  care 
is  bestowed  on  its  culture. 

The  newly  discovered  element,  Rubidium,  has  been 
found  in  the  sugar-beet,  in  tobacco,  coffee,  tea,  and  the 

*  Arendt  was  the  first  to  estimate  sulphuric  acid  in  vegetable  matters  with 
accuracy,  and  to  discriminate  it  from  the  sulphur  in  organic  compounds.  Tliitj 
chemist  determined  the  sulphuric  acid  of  the  oat-plant  by  extracting  the  pulver 
ized  material  with  acidulated  water.  He  likewise  estimated  the  total  sulphur  by 
a  special  method,  and  by  subtracting  the  sulphur  of  the  sulphuric  acid  from  the 
total,  he  obtained  as  a  difference  that  portion  of  sulphur  which  belonged  to  the 
albuminoids,  etc.  In  his  analyses  of  clover,  Ulbricht  followed  a  similar  plan. 
(Vs.  St.,  Ill,  p.  147.)  As  has  already  been  stated,  many  of  the  older  analyse! 
arc  wholly  untrustworthy  ae  -egards  sulphur  and  sulphuric  acid. 


196  HOW   CROPS   GROW. 

grape.  It  doubtless  occurs  perhaps,  together  with  6W 
ftium,  in  many  other  plants,  though  in  very  minute  quan 
tity.  It  is  not  unlikely  that  small  quantities  of  these 
alkali-metals  may  be  found  to  be  of"  decided  influence  on 
the  growth  of  plants.* 

The  late  investigations  of  A.  Braun  and  of  Risse,  (Sachs, 
Exp.  Pliysiologie,  153,)  show  that  Zinc  is  a  usual  ingre 
dient  of  plants  growing  about  zinc  mines,  where  the  soil 
contains  carbonate  or  silicate  of  this  metal.  Certain  mark 
ed  varieties  of  plants  are  peculiar  to,  and  appear  to  have 
been  produced  by,  such  soils,  viz.,  a  violet,  ( Viola  tricolor, 
var.  calaminaris,}\  and  a  shepherd's  purse,  (Thlaspi  al- 
pestre,  var.  calaminaris.)  In  the  ash  of  the  leaves  of  the 
latter  plant,  Risse  found  13° |0  of  oxide  of  zinc;  in  other 
plants  he  found  from  0.3  to  3.3°  |0. 

Copper  is  often  or  commonly  found  in  the  ashes  of 
plants ;  and  other  elements,  viz.,  Arsenic,  Baryta^^.  Lead, 
have  been  discovered  therein,  but  as  yet  we  are  not  fairly 
warranted  in  assuming  that  any  of  these  substances  are  of 
importance  to  agricultural  vegetation.  The  same  is  true 
of  Iodine,  which,  though  an  invariable  and  probably  a 
necessary  constituent  of  many  alga3,  is  not  known  to  exist 
to  any  considerable  extent  or  to  be  essential  in  any  culti 
vated  plants. 

.1*.  •  -;  I 

FUNCTIONS    OF    THE    ASH-INGREDIENTS. 

But  little  is  certainly  known  with  reference  to  the 
subject  of  this  section. 

Sulphates* — The  albuminoids,  which  contain  sulphur  as 
an  essential  ingredient,  obviously  cannot  be  produced  in 
absence  of  sulphuric  acid,  which,  so  far  as  we  know,  is  the 

•  Since  the  above  was  written,  Birner  &  Lncanus  lave  found  that  these 
bodies,  in  the  absence  of  potash,  act  as  poisons  to  the  oat.    { Vs  <S2.,  VIII,  p.  147.J 
t  By  some  botanists  ranked  as  a  distinct  species. 


THE    ASH    OF   PLANTS.  197 

single  source  of  sulphur  to  plants.  The  sulphurized  oils 
of  the  onion,  mustard,  horseradish,  turnip,  etc.,  likewise 
require  sulphates  for  their  organization. 

Phosphates. — The  phosphorized  oils  (protagon)  require 
to  their  elaboration  that  phosphates  or  some  source  of 
phosphorus  be  at  the  disposal  of  the  plant.  The  physio 
logical  function  of  the  phosphates,  so  abundant  in  the  ce 
reals,  admits  of  partial  explanation.  The  soluble  albumi 
noids  which  are  formed  in  the  foliage  must  pass  thence 
through  the  cells  and  ducts  of  the  stem  into  growing  parts 
of  the  plant,  and  into  the  seed,  where  they  accumulate  in 
large  quantity.  But  the  albuminoids  penetrate  membranes 
with  great  difficulty  and  slowness  when  in  the  pure  state. 
According  to  Schumacher,  (Physik  der  Pflanze,  p.  128,) 
the  phosphate  of  potash  considerably  increases  the  diffu 
sive  rate  of  albumin,  and  thus  facilitates  its  translocation 
in  the  plant. 

Alkalies  and  alkali-earths. — The  organic  acids,  viz. : 
oxalic,  malic,  tartaric,  citric,  etc.,  require  alkalies  and  al 
kali-earths  to  form  the  salts  which  exist  in  plants,  e.  g.  bi- 
tartrate  of  potash  in  the  grape,  oxalate  of  lime  in  beet- 
leaves,  malate  of  lime  in  tobacco ;  and  without  these  bases 
it  is,  perhaps,  in  most  cases  impossible  for  the  acids  to  be 
formed,  though  in  the  orange  and  lemon,  citric  acid  exists 
in  the  uncombined  or  free  state,  and  in  various  plants,  as 
Semperviuum  arboreum,  and  Cacalia  ficoides,  acids  are 
formed  during  the  night  which  disappear  in  the  day.  The 
leaves  of  these  plants  are  sour  in  the  morning,  tasteless  at 
noon,  and  bitter  at  night.  (Heyne  &  Link).) 

Silica. — The  function  of  silica  might  appear  to  be,  in  case 
of  the  grasses,  sedges,  and  equisetums,  to  give  rigidity  to 
the  slender  stems  of  these  plants,  and  enable  them  to  sustain 
the  often  heavy  weight  of  the  fruit.  Two  circumstances, 
however,  embarrass  the  unqualified  acceptance  of  this  no 
tion.  The  first  is,  that  the  proportion  of  silica  is  not  great 


19S  Hcrvr  CEOrs  GROW. 

est  in  those  parts  of  the  plant  which,  on  this  view,  would 
most  require  its  presence.  Thus  Norton,  (Am.  Jour,  of 
Sci.,  [2,]  vol.  iii,  pp.  235-6,)  found  that  in  the  sandy  oat 
the  upper  half  of  the  dry  leaf  yielded  16.2  per  cent  ash, 
while  the  lower  half  gave  but  13.6  per  cent.  The  ash  of 
the  upper  part  contained  52.1  per  cent  of  silica,  while  thai 
from  the  bottom  part  ha'd  but  47.8  per  cent  of  this  ingre 
dient.  According  to  Arendt,  (Das  Wachsthum  der  Ha- 
ferpflanze,  p.  180,)  the  different  parts  of  the  oat  contain 
the  following  quantities  of  silica  respectively : 

Amount  of  silica  in  lOOOparfa  of  dry  substance. 

Removed  Insoluble 

by  water.      in  water.  Total. 

Lower  part  of  the  stem 0.33  1.4  1.7 

Middle  part  of  the  stein ...  .0.30  4.8  5.1 

Upper  part  of  the  stem 0.36  13.0  13.3 

Lower  leaves 0.86  34.3  35.2 

Upper  leaves 0.52  43.3  43.8 

We  see  then,  plainly,  that  the  upper  part  of  the  stem 
and  leaves  contains  more  silica  than  the  lower  parts,  while 
the  lower  parts  certainly  need  to  possess  the  greatest 
degree  of  strength. 

We  must  not  forget,  however,  as  Knop  has  remarked, 
that  the  lower  part  of  the  leaf  of  most  cereals  and  grasses 
which  envelopes  the  stem  like  a  sheath,  is  really  the  support 
of  the  plant  as  much  as,  or  even  more,  than  the  stem  itself. 

The  results  of  the  many  experiments  in  water-culture 
by  Sachs,  Knop,  Wolff,  and  others,  (see  p.  186,)  in  which 
the  supply  of  silica  has  been  reduced  to  an  extremely 
small  amount,  without  detriment  to  the  development  of 
plants,  commonly  rich  in  this  substance,  would  seem  to 
demonstrate  that  silica  does  not  essentially  contribute  to 
the  stiffness  of  the  stem. 

Wolff  distinctly  informs  us  that  the  maize  and  oat  plants 
produced  by  him,  in  solutions  nearly  free  from  silica, 
were  is  firm  in  stalk,  and  as  little  inclined  to  lodge  or 
"  lay,-  as  those  which  gre\v  in  the  field. 


THE    ASH    OF    PLANTS.  199 

The  recommendation  to  supply  silex  to  grain  crops,  in 
order  to  stiffen  the  straw  and  prevent  falling  of  the  crop 
oefore  it  ripens,  either  by  directly  applying  alkali-silicates, 
or  by  the  use  of  fertilizers  and  amendments  that  may 
render  the  silica  of  the  soil  soluble,  must,  accordingly,  be 
considered  entirely  futile  from  the  point  of  view  of  the  needs 
of  the  crop,  as  it  is  from  that  of  the  resources  of  the  soil. 

Chlorine. — As  has  been  mentioned,  both  Nobbe  and 
Leydhecker  found  that  buckwheat  grew  quite  well  up  to 
the  time  of  blossom  without  chlorine.  From  that  period 
on,  in  absence  of  chlorine,  remarkable  anomalies  appeared 
in  the  development  of  the  plant.  In  the  ordinary  course 
of  growth,  starch,  which  is  organized  in  the  mature  leaves, 
does  not  remain  in  them  to  much  extent,  but  is  transferred 
to  the  newer  organs,  and  especially  to  the  fruit,  where  it 
also  accumulates  in  large  quantities.  In  absence  of  chlo 
rine,  in  the  experiments  of  Nobbe  and  Leydhecker,  the 
terminal  leaves  became  thick  and  fleshy,  from  extraordinary 
development  of  cell-tissue,  at  the  same  time  they  curled 
together  and  finally  fell  off,  upon  slight  disturbance.  The 
stem  became  knotty,  transpiration  of  water  was  suppress 
ed,  the  blossoms  withered  without  fructification,  and  the 
plant  prematurely  died.  The  fleshy  leaves  were  full  of 
starch-grains,  and  it  appeared  that  in  absence  of  chlorine 
the  transfer  of  starch  from  the  foliage  to  the  flower  and 
fruit  was  rendered  impossible ;  in  other  words,  chlorine  (in 
combination  with  potassium  or  calcium)  was  concluded  to 
be  necessary  to,  was,  in  fact,  the  agent  of  this  transfer. 
Knop  believes,  however,  that  these  phenomena  are  due  to 
some  other  cause,  and  that  chlorine  is  not  essential  to  the 
perfection  of  the  fruit  of  buckwheat,  (see  p.  182). 

Iron. — We  are  in  possession  of  some  interesting  facts, 
which  appear  to  throw  light  upon  the  function  of  this 
metal  in  the  plant.  In  case  of  the  deficiency  of  this  ele 
ment,  foliage  loses  its  natural  green  color,  and  becomes  pale 
or  white  even  in  the  full  sunshine.  In  absence  of  iron  a 


200  HOW    CKOPS    GROW. 

plant  may  unfold  its  buds  at  the  expense  of  already  organ- 
ized  matters,  as  a  potato-sprout  lengthens  in  a  dark  cellar, 
or  in  the  manner  of  fungi  and  white  vegetable  parasites ; 
but  the  leaves  thus  developed  are  incapable  of  assimilating' 
carbon,  and  actual  growth  or  increase  of  total  weight  is 
impossible.  Salm-Horstmar  showed  that  plants  which 
grow  in  soils  or  media  destitute  of  iron,  are  very  pale  in 
color,  and  that  addition  of  iron-salts  very  speedily  gives 
them  a  healthy  green.  Sachs  found  that  maize-seedlings, 
vegetating  in  solutions  free  from  iron,  had  their  first  three 
or  four  leaves  green ;  several  following  were  white  at  the 
base,  the  tips  being  green,  and  afterward,  perfectly  white 
leaves  unfolded.  On  adding  a  few  drops  of  sulphate  or 
chloride  of  iron  to  the  nourishing  medium,  the  foliage  was 
plainly  altered  within  24  hours,  and  in  3  to  4  days  the 
plant  acquired  a  deep,  lively  green.  Being  afterwards 
transferred  to  a  solution  destitute  of  iron,  perfectly  white 
leaves  were  again  developed,  and  these  were  brought  to  a 
normal  color  by  addition  of  iron. 

E.  Gris  was  the  first  to  trace  the  reason  of  these  effects, 
and  first  found,  (in  1843,)  that  watering  the  roots  of  plants 
with  solutions  of  iron,  or  applying  such  solutions  exter 
nally  to  the  leaves,  shortly  developed  a  green  color  where 
it  was  previously  wanting.  By  microscopic  studies  he 
found  that  in  the  absence  of  iron,  the  protoplasm  of  the 
leaf-cells  remains  a  colorless  or  yellow  mass,  destitute  of 
visible  organization.  Under  the  influence  of  iron,  grains 
of  chlorophyll  begin  at  once  to  appear,  and  pass  through 
the  various  stages  of  normal  development.  We  know 
that  the  power  of  the  leaf  to  decompose  carbonic  acid  and 
assimilate  carbon,  resides  in  the  cells  that  contain  chloro 
phyll,  or,  we  may  say,  in  the  chlorophyll-grains  themselves. 
We  understand  at  once,  then,  that  in  the  absence  of  iron, 
which  is  essential  to  the  formation  of  chlorophyll,  there 
can  be  no  proper  growth,  no  increase  at  the  expense  of  the 
eiternal  atmospheric  food  of  vegetation. 


QUANTITATIVE    RELATIONS.  tiOl 

Risse,  under  Sachs'  direction,  (Exp.  Physiologic,  143,) 
demonstrated  that  manganese  cannot  take  the  place  of 
iron  in  the  office  just  described. 

Functions  of  other  Ash-Ingredients, — As  to  the  spe- 
cia1  uses  of  the  other  fixed  matters  we  know  little  It  ap 
pears  to  be  proved  beyond  doubt  that  potash,  li^e,  and 
magnesia,  are  indispensable  to  the  life  and  health  of  ani 
mals,  and  since  all  animals  derive  the  chief  part  c<f  their 
sustenance  from  the  vegetable  world,  it  is  obvious  that 
these  substances  must  be  ingredients  of  plants  in  order  to 
fit  the  latter  for  their  nutritive  office ;  but  why  no  vegeta 
ble  cell  can  be  elaborated  without  potash,  why  lime  and 
magnesia  are  imperative  necessities  to  plants,  we  are  as 
yet  not  able  to  comprehend. 


CHAPTER    EL 


QUANTITATIVE    RELATIONS    AMONG    THE    INGREDIENTS 
OF    PLANTS. 

Various  attempts  have  been  made  to  exhibit  definite 
numerical  relations  between  certain  different  ingredients 
of  plants. 

Equivalent  Replacement  of  Bases,  —  In  1840,  Liebig, 
in  his  Chemistry  applied  to  Agriculture,  suggested  that 
the  various  bases  might  displace  each  other  in  equivalent 
•[iian  tities,  i.  e.,  in  the  ratio  of  their  molecular  weights, 
and  that  were  such  the  case,  the  discrepancies  to  be  observ 
ed  among  analyses  should  disappear,  if  the  latter  were  in 
terpreted  on  this  view.  Liobig  instanced  two  analyses  of 
the  ashes  of  fir-wood  and  t\vo  of  pine-wood  made  by  Ber- 
thier  and  Saussure,  as  illustrations  of  the  correctness  of 
this  theory  In  the  fir  of  Mont  Breven,  carbonate  of 
9* 


HOW  CROPS   GKOW. 

magnesia  was  present ;  in  that  of  Mont  La  Salle,  it  was  ab 
sent.  In  the  former  existed  but  half  as  much  carbonate 
of  potash  as  in  the  latter.  In  both,  however,  the  same 
total  percentage  of  alkali  and  earthy  carbonates  was 
found,  and  the  amount  of  oxygen  in  these  bases  was  the 
Bame  in  both  instances. 

Since  the  unlike  but  equivalent  quantities  of  potash,  lime, 
and  magnesia,  contain  the  same  quantity  of  oxygen,  these 
bases,  in  the  case  in  question,  do  displace  each  other  in 
equivalent  proportions.  The  same  was  true  for  the  ash  of 
pine-wood,  from  Allevard  and  from  Norway.  On  apply 
ing  this  principle  to  other  cases  it  has,  however,  signally 
failed.  The  fact  that  the  plant  can  contain  accidental  or 
unessential  ingredients,  renders  it  obvious  that,  however 
truly  such  a  law  as  that  of  Liebig  may  in  any  case  apply 
to  those  substances  which  are  really  concerned  in  the  vital 
actions,  it  will  be  impossible  to  read  the  law  in  the  results 
of  analyses. 

Relation  of  Phosphates  to  Albuminoids. — Liebig  like 
wise  considers  that  a  definite  relation  must  and  does  exist 
between  the  phosphoric  acid  and  the  albuminoids  of  the 
ripe  grains.  That  this  relation  is  not  constant,  is  evident 
from  the  following  statement  of  the  data,  that  have  been 
as  yet  obtained,  bearing  on  the  question.  In  the  table, 
the  amount  of  nitrogen  (N),  representing  the  albuminoids 
(see  p.  108)  found  in  various  analyses  of  rye  and  wheat 
grain,  is  compared  with  that  of  phosphoric  acid  (PO6), 
the  latter  being  taken  as  unity. 

P05        N. 
Iu   7  Samples  of  Rye-kernel  Fehling  &  Faiszt  found  the  ratio  of 

PO  5  to  N  to  range  from 1 

do  11       do       do       do        Mayer          do  do  do  1 

do   5       do       do       do        Bibra  do  do  do  1 

do   6       do       do       do         Siegert         do          do  do  1 

do  28       do       do       do        the  extreme  range  was  from 1 

do   2       do      of  Wheat-kernel  Fehlinir  &  Fainzt  found  the  ratio  of 

PO  5  to  N  to  range  from 1 

do  11       do       do       dc        Mayer          do          do          do  1 

do   2       do       do       do        Zoeller        do          do          do  1 

do  30       do       do       do        Bibra            do           do           do  1 

do   6       do       do       do        Siegert        do          do          do  1 

do  51       do       do       do        the  extreme  range  was  from 1 


COMPOSITION   IN   SUCCESSIVE    STAGES.  203 

Siegert,  who  has  collected  these  data,  ( Vs.  /S£,  III,  147,) 
and  who  experimented  on  the  influence  of  phosphatic 
and  nitrogenous  fertilizers  upon  the  composition  of  wheat 
and  rye,  gives  as  the  general  result  of  Ids  special  inquiries, 
that  Phosphoric  acid  and  Nitrogen  stand  in  no  constant 
relation  to  each  other.  Nitrogenous  manures  increase  the 
per  cent  of  nitrogen  and  diminish  that  of  phosphoric 
acid. 

Other  Relations. — All  attempts  to  trace  simple  and 
constant  relations  between  other  ingredients  of  plants, 
viz. :  between  starch  and  alkalies,  cellulose  and  silica,  etc., 
etc.,  have  proved  fruitless. 

It  is  much  rather  demonstrated  that  the  proportions  of 
the  constituents  is  constantly  changing  from  day  to  day 
as  the  relative  mass  of  the  individual  organs  themselves 
undergoes  perpetual  variation. 

In  adopting  the  above  conclusions,  it  is  not  asserted 
that  such  genetic  relations  between  phosphates  and  al 
buminoids,  or  between  starch  and  alkalies,  as  Liebig  first 
suggested  and  as  various  observers  have  labored  to  show, 
do  not  exist,  but  simply  that  they  do  not  appear  from 
the  analyses  of  plants. 


THE    COMPOSITION    OF    THE    PLANT    IN    SUCCESSIVE 
STAGES    OF    GROWTH. 

We  have  hitherto  regarded  the  composition  of  the  plant 
mostly  in  a  relative  sense,  and  have  instituted  no  compari 
sons  between  the  absolute  quantities  of  its  ingredients  at 
different  stages  of  growth.  We  have  obtained  a  series  of 
isolated  views  of  the  entire  plant,  or  of  its  parts  at  some 
certain  period  of  its  life,  or  when  placed  under  certain  con 
ditions,  and  have  thus  sought  to  ascertain  the  peculiarities 
of  these  periods  and  to  estimate  the  influence  of  these  con- 


204  HOW   CROPS   GROW. 

ditions.  It  now  remains  to  attempt  in  some  degree  tho 
combination  of  these  sketches  into  a  panoramic  picture — 
to  give  an  idea  of  the  composition  of  the  plant  at  the 
successive  steps  of  its  development.  We  shall  thus  gain 
some  insight  into  the  rate  and  manner  of  its  growth,  anJ 
acquire  data  that  have  an  important  bearing  on  the  requi 
sites  for  its  perfect  nutrition.  For  this  purpose  we  need 
to  study  not  only  the  relative  (percentage)  composition 
of  the  plant  and  of  its  parts  at  various  stages  of  its  exist 
ence,  but  we  must  also  inform  ourselves  as  to  the  total 
quantities  of  each  ingredient  at  these  periods. 

We  shall  select  from  the  data  at  hand  those  which  illus 
trate  the  composition  of  the  oat-plant.  Not  only  the  ash- 
ingredients,  but  also  the  organic  constituents,  will  be  no 
ticed  so  far  our  information  and  space  permit. 

The  Composition  and  Growth  of  the  Oat-Plant  may 

be  studied  as  a  type  of  an  important  class  of  agricultural 
plants,  viz. :  the  annual  cereals — plants  which  complete 
their  existence  in  one  summer,  and  which  yield  a  large 
quantity  of  nutritious  seeds — the  most  valuable  result  of 
culture.  The  oat-plant  was  first  studied  in  its  various 
parts  and  at  different  times  of  development  by  Prof.  John 
Pitkin  Norton,  of  Yale  College.  His  laborious  research 
published  in  1846,  (Trans.  Highland  andAg.  Soc.  1845-7, 
also  Am.  Jour,  of  Sci.  and  Arts,  Vol.  3,  1847,)  was  the 
first  step  in  advance  of  the  single  and  disconnected  anal 
yses  which  had  previously  been  the  only  data  of  the  agri 
cultural  physiologist.  For  several  reasons,  however,  the 
work  of  Norton  was  imperfect.  The  analytical  methods 
employed  by  him,  though  the  best  in  use  at  that  day,  and 
handled  by  him  with  great  skill,  were  not  adapted  to  fur 
nish  results  trustworthy  in  all  particulars.  Fourteen  years 
later,  Arendt,*  at  Moeckern,  and  Bretschneider,f  at  Saarau, 

*  WachsthurnsxerhjltnissederHaferpflanze,  Jour.fu.rPraki,  Chen*.,  76, 191 
t  Dtu  WaohstAwm  dor  Hafffrnflainze,  Leipzig.  1859. 


COMPOSITION   IN   SUCCESSIVE   STAGES.  205 

in  Germany,  at  the  same  time,  but  independently  of  each 
other,  resumed  the  subje.ct,  and  to  their  labors  the  sub 
joined  figures  and  conclusions  are  due. 

Here  follows  a  statement  of  the  Periods  at  which  the 
plants  were  taken  for  analysis. 

i  June  18,  Arendt— Three  lower  leaves  unfolded,  two  upper  still  closed. 
1st  Period  j-     4t    ^  Bretschneider— Four  to  five  leaves  developed. 
2d    Period  I June  30'  (12  davs<)  At.— Shortly  before  the  plants  were  fully  headed. 

)     "     29,  (10  days,)  Br.— The  plants  were  headed. 
M    p-_,nfl  I  July  10,  (10  days,)  At.— Immediately  after  bloom. 

f     "      8,  (9  days,)  Br.-Full  bloom. 
4th  Period  1- July  31' (11  daySl)  At.— Beginning  to  ripen. 

I     "    28,  (20  days,)  Br.— 

5th  Period  i  July  31'  (1°  days')  At~ Fully  ripe' 
>  Aug.    6,   (9  days,)  Br.—    "        " 

It  will  be  seen  that  the  periods,  though  differing  some 
what  as  to  time,  correspond  almost  perfectly  in  regard  to 
the  development  of  the  plants.  It  must  be  mentioned 
that  Arendt  carefully  selected  luxuriant  plants  of  equal 
size,  so  as  to  analyze  a  uniform  material,  (see  p.  210,)  and 
took  no  account  of  the  yield  of  a  given  surface  of  soil. 
Bretschneider,  on  the  other  hand,  examined  the  entire 
produce  of  a  square  rod.  The  former  procedure  is  best 
adapted  to  study  the  composition  of  the  well-nourished 
individual  plant  /  the  latter  gives  a  truer  view  of  the  crop. 

The  unlike  character  of  the  material  as  just  indicated  is 
but  one  of  the  various  causes  which  might  render  the  two 
series  of  observations  discrepant.  Thus,  differences  in 
soil,  weather,  and  seeding,  would  necessarily  influence  the 
relative  as  well  as  the  absolute  development  of  the  two 
crops.  The  results  are, notwithstanding,  strikingly  accord 
ant  in  many  particulars.  In  all  cases  the  roots  were  not 
and  could  not  be  included  in  the  investigation,  as  it  is  im 
possible  to  free  them  from  adhering  soil. 

The  Total  Weight  of  Crop  per  English  acre,  at  the 

end  of  each  period,  was  as  follows : 


206  HOW   CROPS   GKOW. 

TABLE    I.— Br. 

1st  Period,    6,358  Ibs.  avoirdupois. 
2d        "       10,603    "  u 

3d        "       16,523    "  " 

4th       "       14,981    "  « 

5th      "       10,622    "  " 

The  Total  Weights  of  Water  and  Dry  Matter  for  all 

but  the  2d  Period — the  material  of  which  was  accidentally 
lost — were : 

TABLE    II.— Br. 

Dry  Matter,  Water, 

Ibs.  av.  per  acre.    Ibs.  av.  per  acre. 
1st  Period,  1,284  5,074 

3d        "  4,383  12,240 

4th      "  5,427  14,983 

5th      "  6,886  3,736 

1. — From  Tab.  I  it  is  seen :  That  the  weight  of  the  live 
crop  is  greatest  at  or  before  the  time  of  blossom.*  After 
this  period  the  total  weight  diminishes  as  it  had  previously 
increased. 

2. — From  Tab.  II  it  becomes  manifest :  That  the  organic 
tissue  (dry  matter)  continually  increases  in  quantity  up  to 
the  maturity  of  the  plant ;  and 

3. — The  loss  after  the  3d  Period  falls  exclusively  upon 
the  water  of  vegetation.  At  the  time  of  blossom  the  plant 
has  its  greatest  absolute  quantity  of  water,  while  its  least 
absolute  quantity  of  this  ingredient  is  found  when  it  is 
fully  ripe. 

By  taking  the  difference  between  the  weights  of  any 
two  Periods,  we  obtain : 

The  Increase  or  Loss  of  Dry  Matter  and  Water 
during  each  Period. 

TABLE    III.— Br. 

Dry  Matter,  Water, 

Ibs.  per  acre.  Ibs.  per  acre. 

1st  Period,                  1,284  Gain.  5,073  Gain. 

8d        "                        3,099    "  7,106    " 

4th      "                        1,044    "  2,684  Loss. 

5th      "                        1,459    "  5,820      " 

•  In  Arendt's  Experiment*  at  the  time  of  "  heading  oat,"  3d  Period. 


COMPOSITION   IN   SUCCESSIVE    STAGES.  207 

On  dividing  the  above  quantities  by  the  number  of  days 
of  the  respective  periods,  there  results : 

The  Average  Daily  Gain  or  Loss  per  Acre  during 
each  Period. 

TABLE    IV.— Br. 

Dry  Matter.  Water. 

1st  Period,  22  Ibs.  Gain.  87  Ibs.  Gain. 

3d        "  163    "       '•  382    "      u 

4th      "  65    "       "  167    "  Loss. 

5th      "  112    "       "  447    "      " 

4. — Table  III,  and  especially  Tab.  IV,  show  that  the  gain 
of  organic  matter  in  Bretschneider's  oat-crop  went  on 
most  rapidly  at  or  before  the  time  of  blossom,  (according 
to  Arendt  at  the  time  of  heading  out.)  This  was,  then,  the 
period  of  most  active  growth.  Afterward  the  rate  of 
growth  diminished  by  more  than  one-half,  and  at  a  later 
period  increased  again,  though  not  to  the  maximum. 

Absolute  Quantities  of  Carbon,  Hydrogen,  Oxygen, 
Nitrogen,  and  Ash,  in  the  dry  oat  crop  at  the  conclusion  of 
the  several  periods ;  (Ibs.  per  acre.) 

TABLE    V.— Br. 

Carbon.       Hydrogen.      Oxygen.     Nitrogen.  Ash.* 
1st  Period,                 593                80               455             46  110 

3d        "  2,137  286  1,575  122  263 

4th      "  2,600  343  2,043  '      150  291 

5th      "  3,229  405  2,713  167  372 

Relative  Quantities  of  Carbon,  Hydrogen,  Oxygen, 
Nitrogen,  (Organic  Matter,)  and  Ash  in  the  dry  oat  crop, 
at  the  end  of  the  several  Periods ;  (per  cent.) 

TABLE    V-L—  Br. 

Carbon.     Hydrogen.     Oxygen.     Nitrogen.  (Organic  Matter.)  Ash. 

1st  Period,      46.22  6.23  35.39  3.59  91.43  8.57 

3d        "  48.76  6.53  35.96  2.79  94.04  5.96 

4th      "  47.91  6.33  37.65  2.78  94.67  5.33 

5th      "  46.89  5.88  39.40  2.43  94.60  5.40 

*  In  Bretschneider's  analyses,  "ash"  signifies  the  residue  left  after  carefully 
burning  the  plant.  In  Arendt's  investigation  the  sulphur  and  chlorine  were  <1» 
termined  in  the  unburned  plant. 


808  HOW   JROPS   GROW. 

Relatire  Quantities  of  Carbon,  Hydrogen,  Oxygen, 
and  Nitrogen,  in  dry  substance,  after  deducting  the  some 
what  variable  amount  of  ash,  (per  cent). 

TABLE    VII.— Br. 

Carbon.  Hydrogen.  Oxygen.  Nitrogen. 

1st  Period,              50.55                6.81  38.71                3.93 

3d        "                    51.85                6.95  38.34                2.86 

4th      "                    50.55                6.96  39.83                2.93 

5th      "                   49.59                6.21  41.64                2.56 

5. — The  Tables  Y,  VI,  and  VET,  demonstrate  that  while 
the  absolute  quantities  of  the  elements  of  the  dry  oat 
plant  continually  increase  to  the  time  of  ripening,  they  do 
not  increase  in  the  same  proportion.  In  other  words,  the 
plant  requires,  so  to  speak,  a  change  of  diet  as  it  advances 
in  growth.  They  further  show  that  nitrogen  and  ash  are 
relatively  more  abundant  in  the  young  than  in  the  mature 
plant ;  in  other  words,  the  rate  of  assimilation  of  Nitrogen 
and  fixed  ingredients  falls  behind  that  of  Carbon,  Hydro 
gen,  and  Oxygen.  Still  otherwise  expressed,  the  plant  as  it 
approaches  maturity  organizes  relatively  more  amyloids 
and  relatively  less  albuminoids. 

The  relations  just  indicated  appear  more  plainly  when 
we  compare  the  Quantities  of  Nitrogen,  Hydrogen,  and 
Oxygen,  assimilated  during  each  period,  calculated  upon 
the  amount  of  Carbon  assimilated  in  the  same  time  and 
assumed  at  100. 

TABLE    VIII.— Br. 

Carbon.  Nitrogen.  Hydrogen.  Oxygen. 

1st  Period,                 100  •  7.8                   13.4  73.6 

3d        "                     100  4.9                  13.3  72.5 

4th       "                    100  6.1                  12.3  100.8 

5th      "                     100  2.6                  10.6  106.5 

From  Table  VIII  we  see  that  the  ratio  of  Hydrogen  to 
Carbon  regularly  diminishes  as  the  plant  matures ;  that  of 
Nitrogen  falls  groatly  from  the  infancy  of  the  plant  to  the 
period  of  full  bloom,  then  strikingly  increases  during  the 


COMPOSITION   IN   SUCCESSIVE    STAGES.  209 

fiist  stages  of  ripening,  but  falls  off  at  last  to  minimum. 
The  ratio  of  Oxygen  to  Carbon  is  the  same  during  the  1st 
and  3d  periods,  but  increases  remarkably  from  the  period 
of  full  blossom  until  the  plant  is  ripe. 

As  already  stated,  the  largest  absolute  assimilation  of 
all  ingredients  —  most  rapid  growth  —  takes  place  at  the 
time  of  heading  out,  or  blossom.  At  this  period  all  the 
volatile  elements  are  assimilated  at  a  nearly  equal  rate, 
and  at  a  rate  equal  to  that  at  which  the  fixed  matters  (ash) 
are  absorbed.  In  the  first  period  Nitrogen  and  Ash  ;  in 
the  fourth  period  Nitrogen  and  Oxygen;  in  the  fifth  pe 
riod  Oxygen  and  Ash  are  assimilated  in  largest  propor 
tion. 

This  is  made  evident  by  calculating  for  each  period  the 
Daily  Increase  of  Each  Ingredient,  the  amount  of  the  in 
gredients  in  the  ripe  plant  being  assumed  at  100  as  a  point 
of  comparison.  The  figures  resulting  from  such  a  calcula 
tion  are  given  in 

TABLE    IX.—  Br. 


Carbon. 

Hydrogen. 

Oxygen. 

Nitrogen. 

A.sh. 

1st  Period, 

0.31 

0.33 

0.28 

0.47 

0.50 

3d 

2.51 

2.68 

2.17 

2.39 

2.13 

4th      " 

0.89 

0.83 

1.07 

1.06 

0.47 

5th      " 

1.49 

1.16 

1.89 

0.75 

1.70 

The  increased  assimilation  of  the  5th  over  the  4in  period 
is,  in  all  probability,  only  apparent.  The  results  of  anal 
ysis,  as  before  mentioned,  refer  only  to  those  parts  of  the 
plant  that  are  above  ground.  The  activity  of  tae  foliage 
in  gathering  food  from  the  atmosphere  is  doubtless  greatly 
diminished  before  the  plant  ripens,  as  evidenced  by  the 
loaves  turning  yellow  and  losing  water  of  vegetation. 
The  increase  of  weight  in  the  plant  above  ground  probably 
proceeds  from  matters  previously  stored  in  the  roots,  which 
now  are  transferred  to  the  fruit  and  foliage,  and  maintain 
the  growth  of  these  parts  after  their  power  of  assimilatirg 
inorganic  food  (COa,  HaO,  NH,,  NaOB)  is  lost. 


210  HOW   CROPS   GRoW. 

The  following  statement  exhibits  the  Average  Daily  In 
crease  of  Carbon,  Hydrogen,  Oxygen,  Nitrogen,  and  Ash, 

(in  Ibs.  per  acre)  during  the  several  periods. 

TABLE    X.—  Br. 

Carbon.  Hydrogen.  Oxygen.  Nitrogen.  Ash. 

1st  Period,              8.43           1.13  6.30            0.65  1.56 

3d        "                 66.95           8.94  48.06            3.30  6.55 

4th      "                  23.84           2.95  24.06             1.47  1.44 

5th      "                 39.85           3.89  43.44            1.04  5.23 

Turning  now  to  Arendt's  results,  which  are  carried  more 
into  detail  than  those  of  Bretschneider,  we  will  notice 

A, — The  Relative  (percentage)  Composition  of  the 
Entire  Plant  and  of  its  Parts*  during  the  several  periods 
of  vegetation. 

1.  Fiber  \  is  found  in  greatest  relative  quantity — 40°  |0 — 
in  the  lower  joints  of  the  stem,  and  from  the  time  when 
the  grain  "  heads  out,"  to  the  period  of  bloom.  Relatively 
considered,  there  occur  great  variations  in  the  same  part 
of  the  plant  at  diiferent  stages  of  growth.  Thus,  in  the 
ear,  which  contains  the  least  fiber,  the  quantity  of  this 
substance  regularly  diminishes,  not  absolutely,  but  only 
relatively,  as  the  plant  becomes  older,  sinking  from  27°  |0, 
at  heading,  to  12°  |0,  at  maturity.  In  the  leaves,  which,  as 
regards  fiber,  stand  intermediate  between  the  stem  and 
ear,  this  substance  ranges  from  22°  |0  to  38°  |0.  Previous 
to  blossom,  the  upper  leaves,  afterwards  the  lower  leaves, 
are  the  richest  in  fiber.  In  the  lower  leaves  the  maximum, 

*  Arendt  selected  large  and  well-developed  plants,  divided  them  into  six  parts, 
and  analyzed  each  part  separately.  His  divisions  of  the  plants  were  1,  the  thrco 
lowest  joints  of  the  stem  ;  2,  the  two  middle  joints ;  3,  the  upper  joint ;  4,  th« 
three  lowest  leaves ;  5,  the  two  upper  leaves ;  6,  the  ea.r.  The  stems  were  cut 
Just  above  the  nodes,  the  leaves  included  the  sheaths,  the  ears  were  stripped  from 
the  stem.  Arendt  rejected  all  plants  which  were  not  perfect  when  gathered. 
When  nearly  ripe,  the  cereals,  as  is  well  known,  often  lose  one  or  more  of  their 
lower  leaves.  For  the  numerous  analytes  on  which  these  conclusions  are  baaed 
We  must  refer  to  the  original. 

t  i.  e.,  Crude  cellulose  ;  see  p.  60. 


COMPOSITION    D*  SUCCESSIVE    STAGES.  211 

(33J|0,)  is  found  in  the  4th;  in  the  upper  leaves,  (38°  |c  )  in 
the  2d  period. 

The  apparent  diminution  in  amount  of  fiber  is  due  in 
all  cases  to  increased  production  of  other  ingredients. 

2«  Jfat  and  Wax  are  least  abundant  in  the  stem.  Their 
proportion  increases,  in  general,  in  the  upper  parts  of  the 
stem,  as  well  as  in  the  later  stages  of  its  growth.  The 
range  is  from  0.2°  |0  to  3°|0.  In  the  ear  the  proportion  in 
creases  from  2°|0  to  3.7°  |0.  In  the  leaves  the  quantity  is 
much  larger  and  is  mostly  wax.  The  smallest  proportion 
is  4.8°  1 0,  which  is  found  in  the  upper  leaves,  when  the 
plant  is  ripe.  The  largest  proportion,  (10°  |0,)  exists  in 
the  lower  leaves,  at  the  time  of  blossom.  The  relative 
qu  an  titles  found  in  the  leaves  undergo  considerable  varia 
tion  from  one  stage  of  growth  to  another. 

3*  Non-nitrogenous  matters,  other  than  fiber, — starch, 
si '.gar,  etc.* — undergo  great  and  irregular  variation.  In 
the  stem  the  largest  percentage,  (57°|OJ)  is  found  in  the 
young  lower  joints;  the  smallest,  (43°|  OJ)  in  ripe  upper 
straw.  Only  in  the  ear  occurs  a  regular  increase,  viz., 
from  54  to  63°  |0. 

4.  The  Albuminoids, \  in  Arendt's  investigation,  exhibit 
a  somewhat  different  relation  to  the  vegetable  substance, 
from  what  was  observed  by  Bretschneider,  as  seen  from 
the  subjoined  comparison  of  the  percentages  found  at  the 
different  periods. 

Periods. 

I.            II.           III.  IV.           V. 

Arendt 20.93        11.65        10.86  13.67  14.30 

Bretschueider 23.73                      1-.7.67  17.61  1539 

These  differences  may  be  variously  accounted  for.  They 
are  due,  in  part,  to  the  fact  that  Arendt  analyzed  only 
large  and  perfect  plants.  Bretschneider,  on  the  other 

*  What  remains  after  deducting  fat  and  wax,  albuminoids,  fiber,  and  ana, 
from  the  dry  substance,  is  here  included. 

t  Calculated  by  multiplying  the  percentage  of  nitrogen  by  6.88. 


212  HOW   CROPS    GROW. 

hand,  examined  all  the  plants  of  a  given  plot,  large  and 
small,  perfect  and  injured.  The  differences  illustrate  what 
has  been  already  insisted  on,  viz.,  that  the  development 
of  the  plant  is  greatly  modified  by  the  circumstances  of  its 
growth,  not  only  in  reference  to  its  external  figure,  but  also 
as  regards  its  chemical  composition. 

The  relative  distribution  of  nitrogen  in  the  parts  of  the 
plant  at  the  end  of  the  several  periods  is  exhibited  by  the 
following  table,  simple  inspection  of  which  shows  the  fluc 
tuations,  (relative,)  in  the  content  of  this  element.  The 
percentages  are  arranged  for  each  period  separately,  pro 
ceeding  from  the  highest  to  the  lowest: 

PERIODS. 

I.                  II.  III.                 IV.                 V. 
Upper  leaves.  Lower  leaves.  Upper  leaves.          Ears.                Ears. 

3.74                   2.39  2.27"                  2.85                   3.04 

Lower  leaves.  Upper  leaves.  Lower  leaves.  Upper  leaves.  Upper  leaves. 

3.38                   2.19  2.18                   1.91                   1.74 

Lower  leaves.          Ears  Ears.         Lower  leaves.  Upper  stem. 

2.15                  2.06  1.85                  1.63                  1.56 

Middle  stem.   Upper  stem.    Upper  stem.  Lower  leaves 

1.53  1.34                   1.60                   1.43 

Upper  stem.  Middle  stem.  Middle  stein.  Middle  stein. 

0.87  0.98                   1.20                   1.17 

Lower  stem.  Lower  stem.    Lower  stem.  Lower  stem. 

0.80  0.88                  0.83                  0.79 

5.  Ash. — The  agreement  of  the  percentages  of  ash  in  the 
entire  plant,  in  corresponding  periods  of  the  growth  of  the 
oat,  in  the  independent  examinations  of  Bretschneider  and 
Arendt  is  remarkably  close,  as  appears  from  the  figures 
below. 

PERIODS. 
I.  II.  III.  IV.  V. 

Bretschneider 8.57  5.96          5.33         5.40 

Arendt 8.03          5.24          5.44         5.30          5.17 

The  diminution  at  the  2d,  increase  at  the  3d,  and  sub 
sequent  diminution  at  the  4th  period,  are  observed  to  run 
parallel  in  both  cases. 

As  regards  the  several  parts  of  the  plant,  it  was  found 


COMPOSITION   IN   SUCCESSIVE    STAGES.  213 

by  A  rend  t  that  of  the  stem  the  upper  portion  was  richest  in 
ash  throughout  the  whole  period  of  growth.  Of  the  leaves, 
on  the  contrary,  the  lower  contained  most  fixed  matters. 
In  the  ear  there  occurred  a  continual  decrease  from  its 
first  appearance  to  its  maturity,  while  in  the  stem  and 
leaves  there  was,  in  general,  a  progressive  increase  towards 
the  time  of  ripening.  The  greatest  percentage,  (10.5°  |0,) 
was  found  in  the  ripe  leaves;  the  smallest,  (0.78° |0?)  in  the 
ripe  lower  straw. 

Far  more  interesting  and  instructive  than  the  relative 
proportions  are 

B — The  absolute  quantities  of  the  ingredients  found 
in  the  plant  at  the  conclusion  of  the  several  periods  of 
growth. — These  absolute  quantities,  as  found  by  Arendt, 
in  a  given  number  of  carefully  selected  and  vigorous 
plants,  do  not  accord  with  those  obtained  by  Bretschnei- 
der  from  a  given  area  of  ground,  nor  could  it  be  expected 
that  they  should,  because  it  is  next  to  impossible  to  cause 
the  s^rae  amount  of  vegetation  to  develope  on  a  number 
of  distinct  plots. 

Though  the  results  of  Bretschneider  more  nearly  rep 
resent  the  crop  as  obtained  in  farming,  those  of  Arendt  give 
a  truer  idea  of  the1  plant  when  situated  in  the  best  possible 
conditions,  and  attaining  a  uniformly  high  development. 
We  shall  not  attempt  to  compare. the  two  sets  of  observa 
tions,  since,  strictly  speaking,  in  most  points  they  do  not 
admit  of  comparison. 

From  a  knowledge  of  the  absolute  quantities  of  the  sub 
stances  contained  in  the  plant  at  the  ends  of  several  periods, 
we  may  at  once  estimate  the  rate  of  growth,  i.  e.,  the  rapid- 
itrwith  which  the  constituents  of  the  plant  are  either  taken 
np  or  organized. 

The  accompanying  table,  which  gives  in  alternate  col 
umns  the  total  weights  of  1,000  plants  at  the  end  of  the 
several  periods,  and,  (by  subtracting  the  first  from  the 


214 


HOW   CROPS   GROW. 


second,  the  second  from  the  third,  etc.,)  the  gain  from 
matters  absorbed  or  produced  during  each  period,  wil.. 
serve  to  justify  the  deductions  that  follow,  which  are  taken 
from  the  treatise  of  Arendt,  and  which  apply,  of  course, 
only  to  the  plants  examined  by  this  investigator. 

1,000  ENTIRE  PLANTS,  (WATER-FREE.) 


Contain  at 
end  of  Oftd 

absorb  or 
produce 

with  in 

Contain 
at 
end  of 

Abnorb  or 
produce 
within 

"2^0 

o     ~ 

^ 

Absorb  o.?' 
produce 
wit/tin 

n 

Absorb  or 
produce 
within 

"2      *O 

fl 

Absorb  or 
prodltce 
within 

Period  I. 

3  leaves 
open.* 

Period  II. 
Heading 
out. 

Period  III. 

Blossomed. 

Period  IV. 
Beg  ining 
to     pen. 

Period  V. 
Ripe. 

Fiber  

103.3 
20.1 

201.4 
95.4 

459.71  356.4 
4S.9     2*.« 
624.6    42:^.2 
158.S]    63.5 

56  4.  S 
82.9 
916.7 
202.8 

105.1     515. 
3t.0i    97. 

2'.I2.1  1-21-2.0 
43.9    317.8 

io.v.f 
14.7 
325.9 
115.0 

550.6 
S9.S 
1340.0 
351.6 

Loss 
Lota 

97.4 
34.2 

Fat  [matters 

Other    non  -  nitrogenous 
Albuminoids  

Organic  matter  

419.2 

1292.  2!  813.0 

17ii7.2 

475.1  2203.0 

43'..  S  2331.  G 

128.6 

Silica  

6.39 
1.06 
3.27 
0.20 
4.43 
1.53 
2.28 
0.86 
17.05 

36.60 

15.32 
2.71 
5.  TO 
0  46 
8.5') 
2.71 
3.6'2 
1.28 
31.11 

9.43 

1.65 
2.72 
0.2!i 
4.02 
1.18 
1.84 
0.42 
14.06 

25.45 
2.6-i 
10.32 
0.61 
ll.iii 
3  71 
o  32 
1.47 
40.  -2.) 

100.41 

9.63 
0 
4.33 
0.15 

11? 

1.70 
0.19 
9.03 

30..  '33 

34.66 
4  83 
12.90 
O.S3 
14.49 
5.42 

?:?•; 

4K33 
1-20.75 

9.21 

O    ]•> 

2!  58 

0.22 
2.89 
1.71 
0.64 
Low 
4.13 

20.31 

36.32 
5.34 
14.23 
0.5S 
14.71 
6.45 
5.78 
O.S7 
43.76 

126.93 

i.r>6 
0.41 
1,91 

Lox* 
0.22 
1.08 
Low 
Lo-sa 
Low 

7.18 

Sulphuric  acid  

Phosphoric  acid  

Oxide  of  iron  

Li  -lie 

Mngnesia  

Chlorine 

Soda 

Potash. 

Ash      .      .     . 

70.  0-! 

33.4-i 

Dry  Matter  

455.8 

1353.  G 

907.8 

iscr.6 

504.0 

2323.8 

456.2 

•2458.5 

134  7 

1.  The  plant  increases  in  total  weight,  (dry  matter,) 
through  all  its  growth,  but  to  unequal  degrees  in  different 
periods.     The  greatest  growth  occurs  at  the  time  of  head 
ing  out ;  the  slowest,  within  ten  days  of  maturity. 

We  may  add  that  the  increase  of  the  oat  after  blossom 
takes  place  mostly  in  the  seed,  the  other  organs  gaining 
but  little.  The  lower  leaves  almost  cease  to  grow  after 
the  2d  period. 

2.  Fiber  is  produced  most  largely  at  the  time  of  head 
ing  out,  (2d  period.)     When  the  plant  has  finished  blos 
soming,  (end  of  3d  period,)  the  formation  of  fiber  entirely 
ceases.   Afterward  there  appears  to  occur  a  slight  dirninu- 

»  The  weights  in  this  table  are  grams.  One  gram  =  15.4&4  grains.  As  tho 
weights  have  mostly  a  comparative  value,  reduction  to  the  English  standard  it 
unnecessary 


COMPOSITION   IN    SUCCESSIVE    STAGES.  215 

tion  of  this  substance,  probably  due  to  unavoidable  loss 
of  lower  leaves,  but  not  to  a  resorption  or  metamorphosis 
in  the  plant. 

3,  Fat  is  formed  most  largely  at  the  time  of  blossom.  It 
ceases  to  be  produced  some  weeks  before  ripening. 

4.  The  formation  of  Albuminoids  is  irregular.      The 
greatest  amount  is  organized  during  the  4th  period,  (after 
blossoming.)     The  gain  in  albuminoids  within  this  period 
is  two-fifths  of  the  total  amount  found  in  the  ripe  plant, 
and  also  is  nearly  two-fifths  of  the  entire  gain  of  organic 
substance  in  the  same  period.     The  absolute  amount  or 
ganized  in  the  1st  period  is  not  much  less  than  in  the  4th, 
but  in  the  2d,  3d,  and  5th  periods,  the  quantities  are  con 
siderably  smaller. 

Bretschneicler  gives  the  data  for  comparing  the  produc 
tion  of  albuminoids  in  the  oat  crop  examined  by  him  with 
Arendt's  results.  Taking  the  quantity  found  at  the  con«^ 
elusion  of  the  1st  period  as  100,  the  amounts  gained  during 
the  subsequent  periods  are  related  as  follows : 

PERIODS. 
I.  II.          III.  (II  &  III.)   IV.    (II,  III  &  IV.)   V. 

Arendt 100        67        46        (113)        120  (233)  36 

Bretschneider . .  .100        ?          ?         (165)         62  (227)  3!> 

We  perceive  striking  differences  in  the  comparison,  hi 
Bretschneider's  crop,  the  increase  of  albuminoids  goes  on 
most  rapidly  in  the  3d  period,  and  sinks  rapidly  du)  mg 
the  time  when  in  Arendt's  plants  it  attained  the  maximum. 
Curiously  enough,  the  gain  in  the  2d,  3d,  and  4th  periods, 
taken  together,  is  in  both  cases  as  good  as  identical,  (233 
and  227,)  and  the  gain  during  the  last  period  is  also  equal. 
This  coincidence  is  doubtless,  however,  merely  accidental. 
Comparisons  with  other  crops  of  oats,examined,though  very 
incompletely,  by  Stockhardt,  (Chemischer  Ackersmann, 
1855,)  and  Wolff,  (Die  Erschopfttng  des  Bodens  durch  die 
Cultur,  1856,)  demonstrate  that  the  rate  of  assimilation  is 
not  related  to  any  special  times  or  periods  of  develop//  eut, 


216  HOW   CROPS    GROW. 

but  depends  upon  the  stores  of  food  accessible  to  the  plant 
and  the  favor ableness  of  the  iveather  to  growth. 

The  following  figures,  which  exhibit  for  each  period  of 
both  crops  a  comparison  of  the  gain  in  albuminoids  with 
the  increase  of  the  other  organic  matters,  further  demon 
strate  that  in  the  act  of  organization,  the  nitrogenous  prin 
ciples  have  no  close  quantitative  relations  to  the  non-ni 
trogenous  bodies,  (amyloids  and  fats.) 

The  quantities  of  albuminoids  gained  during  each  period 
being  represented  by  10,  the  amounts  of  amyloids,  etc., 
are  seen  from  the  subjoined  ratios : 

PERIODS. 

Ratio  in 
I.  II  &  III.          IV.  V.  Ripe  Bant. 

Arendt 10:34        10:114        10:28      10:    25        10:66 

Bretschneider..lO  :  30        10  :    50-       10  :  46      10  :  120        10  :  51 

5«  The  Ash-ingredients  of  the  oat  are  absorbed  through 
out  its  entire  growth,  but  in  regularly  diminishing  quan 
tity.  The  gain  during  the  1st  period  being  10,  that  in  the 
2d  period  is  9,  in  the  3d,  8,  in  the  4th,  5-J-,  in  the  5th,  2 
nearly. 

The  ratios  of  gain  in  ash-ingredients  to  that  in  entire 
dry  substance,  are  as  follows,  ash-ingredients  being  as 
sumed  as  1,  in  the  successive  periods : 

1  :  12J,     1  :  27,     1  :  16,     1  :  23,     1  :  19. 
Accordingly,  the  absorption  of  ash-ingredients  is  not  pro 
portional  to  the  growth  of  the  plant,  but  is  to  some  degree 
accidental,  and  independent  of  the  wants  of  vegetation. 

Recapitulation. — Assuming  the  quantity  of  each  proxi 
mate  element  in  the  ripe  plant  as  100,  it  contained  at  the 
end  of  the  several  periods  the  following  amounts  : 

Fiber.  Fat.  Amyloids.  Albuminoids.  Ash. 

I.  Period,              18"  |0  20"  |0  15"  |0              27°  |0  20°  |. 

II.   "        81  "  50  "  47  "      45  "      55  " 

III.   "       100  "  85  u  70  u      57 "      79 " 

[V.   "       100 "  100  "  92  "      90 "      95 " 

V.   "       100  "  100 "  100  "     100 "  100 4< 


COMPOSITION   IN   SUCCESSIVE   STAGES.  217 

The  gain  during  each  period  was  accordingly  as  fol 
lows: 

I.  Period, 
II.   " 

III.  " 

IV.  » 
V   " 

100 "     100 "     100  "     100  "     100 " 

6. — As  regards  the  individual  ingredients  of  the  ash, 
the  plant  contained  at  the  end  of  each  period  the  follow 
ing  amounts, — the  total  quantity  in  the  ripe  plant  being 
taken  at  100.  Corresponding  results  from  Bretschneider 
enclosed  in  (  )  are  given  for  comparison. 


Fiber. 

Fat. 

Amyloids. 

Albuminoids. 

Ash. 

18°  lo 
63" 

SO"  |0 
30  " 

15°  |0 
32  " 

27°|0 
18  u 

290  10 
26" 

19  " 

35" 

23" 

12  " 

24" 

0  " 

15" 

22" 

33  u 

16  " 

0  " 

0  " 

8" 

10  " 

5" 

Silica.         uc       'TcTC      Lime'       Ms™**"'      Pf>ta*h- 
Per  cent.       Per  cent.     Per  cent.       Per  cent.      Per  cent.      Per  cent. 
I.  Period,      18    (  22)         20    (  43)         23    (23)         80    (  31)         24    (31)         89    (  42) 

III!       «  %}<*>        II\(W         73J(63>         3{  <«         $  !(73)         9?|<89> 

IV.   "     93  (  72)    90  (  39)    91  (74)    99  (  74)    84  (  77)   100  (100) 

V.   "    100  (100)   100  (100)   100  (100)   100  (100)   100  (100)   100  (95*) 

The  gain  (or  loss,  indicated  by  the  minus  sign  — )  in 
these  ash-ingredients  during  each  period  is  given  below. 


Lime.        Magnesia .       Potash. 

Per  cent.     Per  cent.     Per  cent.         Per  cent.      Per  cent.      Per  cent. 
I.  Period,    18    (  22)        20    (  42  )         23    (  23)        30    (  31  )       24    (  31)         39    (  42  ) 

iii:    «    »}c«)    *o\<.  2>     3i!(40>    iil(52>    SK43'    i!J(47> 

IV.   "    23  (  15)    3S  (-5»)    18  (  10)   20  (— 9«)   26  (  4  )    9  (  11  ) 
V.   "     7  (  28)    10  (  56  )     9  (  21)    1  (  17  )    16  (  23)     0  (-5*) 

100  (100)   100   (100)   100  (100)   100  (100)   100  (100)    100  (100) 

These  two  independent  investigations  could  hardly  give 
all  the  discordant  results  observed  on  comparing  the  above 
figures,  as  the  simple  consequence  of  the  unlike  mode  of 
conducting  them.  We  observe,  for  example,  that  in  the 
last  period  Arendt's  plants  gathered  less  silica  than  in  any 
other — only  7°|0  of  the  whole.  On  the  other  hand,  Bret- 
schneider's  crop  gained  more  silica  in  this  than  in  any 

*  In  these  instances  Bretschn cider's  later  crops  contained  less  sulphuric  acid,  lime, 
and  potash,  than  the  earlier.  This  result  may  be  due  to  the  washing  of  the  crap  toy 
r^ins,  but  is  orobably  caused  by  unequal  development  of  the  several  plots. 

10 


218  HOW   CROPS   GROW. 

other  single  period,  viz.:  28° |0.  A  similar  statement  is 
true  of  phosphoric  acid.  It  is  obvious  that  Bretschriei- 
der's  crop  was  taking  up  fixed  matters  much  more  vigor- 
ously  in  its  last  stages  of  growth,  than  were  Arendt's 
plants.  As  to  potash  we  observe  that  its  accumulation 
ceased  in  the  4th  period  in  both  cases. 

It  is,  on  the  whole,  plain  that  we  cannot  safely  draw  from 
these  interesting  researches  any  very  definite  conclusions 
as  to  the  rate  and  progress  of  assimilation  and  growth  in 
the  oat  plant,  beyond  what  have  been  already  pointed  out. 

C,— Translocation  of  substances  in  the  Plant,— The 
translocation  of  certain  matters  from  one  part  of  the  plant 
to  another  is  revealed  by  the  analyses  of  Arendt,  and 
since  such  changes  are  of  interest  from  a  physiological 
point  of  view,  we  may  recount  them  here  briefly. 

It  has  been  mentioned  already  that  the  growth  of  the 
stem,  leaves,  and  en r,' of  the  oat  plant  in  its  later  stages 
probably  takes  place  to  a  great  degree  at  the  expense  of 
the  roots.  It  is  also  probable  that  a  transfer  of  amyloids, 
and  certain  that  one  of  albuminoids,  goes  on  from  tlw 
leaves  through  the  stem  into  the  ear. 

Silica  appears  not  to  be  subject  to  any  change  of  posi 
tion  after  it  has  once  been  fixed  by  the  plant.  Chlorine 
likewise  reveals  no  noticeable  mobility. 

On  the  other  hand  phosphoric  acid  passes  rapidly  from 
the  leaves  and  stem  towards  or  into  the  fruit  in  the  earlier 
as  \vell  as  in  the  later  stages  of  growth,  as  shown  by  the 
following  figures : 

O         O 

1,000  plants  contained  in  the  various  periods,  quantities 
(grams)  of  phosphoric  acid  as  follows: 

1st  Period.  Ad  Period.  3d  Period.  Uh  Period.  Mh  Period. 

3  lower  joints  of  stem  0.47  0  "20  0.21           0.20  0.19 

2  middle      "          "  0.39  l.H           0.46  0.18 
Uppn-  joint            "  0.66  1.73            0.31  0.39 
a  lower  leaves        «  1.05  070  0.09           0.61  0.85 

3  upper  leaves       "  1.75  1.07  1.18           0.74  0.59 
Ear  —  2.36  536  10.07  12.53 


COMPOSITION   IN   SUCCESSIVE    STAGES.  219 

Observe  that  these  absolute  quantities  diminish  in  the 
stem  and  leaves  after  the  1st  or  3d  period  in  all  cases,  and 
increase  very  rapidly  in  the  ear. 

Arendt  found  that  sulphuric  acid  existed  to  a  much 
greater  degree  in  the  leaves  than  in  the  stem,  throughout 
the  entire  growth  of  the  oat  plant,  and  that  after  blos 
soming  the  lower  stem  no  longer  contained  sulphur  in  the 
form  of  sulphuric  acid  at  all,  though  its  total  in  the  plant 
considerably  increased.  It  is  almost  certain,  then,  that 
sulphuric  acid  originates,  either  partially  or  wholly,  by 
oxidation  of  sulphur  or  some  sulphurized  compound,  in 
the  upper  organs  of  the  oat. 

Magnesia  is  translated  from  the  lower  stem  into  the 
ipper  organs,  and  in  the  fruit,  especially,  it  constantly  in 
creases  in  quantity. 

There  is  no  evidence  that  lime  moves  upward  in  the 
plant.  On  the  contrary,  Arendt's  analyses  go  to  show 
that  in  the  ear  during  the  last  period  of  growth,  it  dimin 
ishes  in  quantity,  being,  perhaps,  replaced  by  magnesia. 

As  to  potash,  no  transfer  is  fairly  indicated  except  from 
the  ears.  These  contained  at  blossoming  (period  III)  a 
maximum  of  potash.  During  their  subsequent  growth 
the  amount  of  potash  diminished,  being  probably  displac 
ed  by  magnesia. 

The  data  furnished  by  Arendt's  analyses,  while  they  in 
dicate  a  transfer  of  matters  in  the  cases  just  named  and  in 
most  of  them  with  great  certainty,  do  not  and  cannot  from 
their  nature  disprove  the  fact  of  other  similar  changes,  and 
cannot  fix  the  real  limits  of  the  movements  which  they 
point  out. 


DIVISION   II. 

THE    STRUCTURE    OF    THE     PLANT    AND 
OFFICES    OF    ITS    ORGANS. 

CHAPTER    L 

GENERALITIES. 

We  have  given  a  brief  description  of  those  elements 
and  compounds  which  constitute  the  plant  in  a  chemical 
sense.  They  are  the  materials— the  stones  and  timbers,  so 
to  speak — out  of  which  the  vegetable  edifice  is  built.  It 
is  important  in  the  next  place  to  learn  how  these  building 
materials  are  put  together,  what  positions  they  occupy 
what  purposes  they  serve,  and  on  what  plan  the  edifice  is 
constructed. 

It  is  impossible  for  the  builder  to  do  his  work  until  lie 
has  mastered  the  plans  and  specifications  of  the  architect. 
So  it  is  hardly  possible  for  the  farmer  with  certainty  to 
contribute  in  any  great,  especially  in  any  new  degree,  to 
the  upbuilding  of  the  plant,  unless  he  is  acquainted  with 
the  mode  of  its  structure  and  the  elements  that  form  it. 
It  is  the  happy  province  of  science  to  add,  to  the  vague  and 
general  information  which  the  observation  and  experience 
of  generations  has  taught,  a  more  definite  and  particular 
knowledge, — a  knowledge  acquired  by  study  purposely 
and  carefully  directed  to  special  ends. 

An  acquaintance  with  the  parts  and  structure  of  the  plant 
ia  indispensable  fi.r  understanding  the  mode  by  which 
220 


ORGANS  OF  THE  PLANT.  221 

i*  derives  its  food  from  external  sources,  while  the  ing^n- 
K  as  methods  of  propagation  practiced  in  fruit  and  flower 
culture  are  only  intelligible  by  the  help  of  this  knowledge. 

ORGANISM  OF  THE  PLANT.  —  We  have  at  the  outset 
spoken  of  organic  matter,  of  organs  and  organization. 
It  is  in  the  world  of  life  that  these  terms  have  their  fittest 
application.  The  vegetable  and  animal  consist  of  numer 
ous  parts,  differing  greatly  from  each  other,  but  each  essen 
tial  to  the  whole.  The  root,  stem,  leaf,  flower,  and  seed, 
are  each  instruments  or  organs  whose  co-operation  is  need 
ful  to  the  perfection  of  the  plant.  The  plant  (or  animal), 
being  thus  an  assemblage  of  organs,  is  called  an  Organism; 
it  is  an  Organized  or  Organic  Structure.  The  atmos 
phere,  the  waters,  the  rocks  ai-i  soils  of  the  earth,  are 
mineral  matters ;  they  are  inorganic  and  lifeless. 

In  inorganic  nature,  chemical  affinity  rules  over  the 
transformations  of  matter.  A  plant  or  animal  that  is 
dead,  under  ordinary  circumstances,  soon  loses  its  form  and 
characters ;  it  is  gradually  consumed  by  the  atmospheric 
oxygen,  and  virtually  burned  up  to  air  and  ashes. 

In  the  organic  world  a  something,  which  we  call  the 
Vital  Principle,  resists  and  overcomes  or  modifies  the  af 
finities  of  oxygen,  and  ensures  the  existence  of  a  con 
tinuous  and  perpetual  succession  of  living  forms. 

The  organized  structure  is  characterized  and  distinguish- 
ed  from  mineral  matter  by  two  particulars : 

1.  It  builds  up  and  increases  its  own  mass  by  appropri 
ating  external  matter.     It  assimilates  surrounding  sul> 
stances.     It  grows  by  the  absorption  of  food. 

2.  It  reproduces  itself.     It  comes  from,  and  forms  again 
a  seed  or  germ. 

ULTIMATE  AND  COMPLEX  ORGANS. — In  our  account  of 
the  Structure  of  the  Plant  we  shall  first  consider  the  ele 
ments  of  that  structure — the  Primary  Organs  or  Vegetable 
Cells — which  cannot  be  divided  or  wounded  without  ex- 


HOW   CROPS   GROW, 

tiugaishiiig  their  life,  and  by  whose  expansion  or  multipli 
cation  all  growth  takes  place.  Then  will  follow  an  account 
of  the  complex  parts  of  the  plant — its  Compound  Organs 
— which  are  built  up  by  the  juxtaposition  of  numerous 
cells.  Of  these  we  have  one  class,  viz. :  the  Roots,  Stems, 
and  Leaves,  whose  office  is  to  sustain  and  nourish  the  Indi 
vidual  Plant.  These  may  be  distinguished  as  the  Vege 
tative  Organs.  The  other  class,  comprising  the  Flower 
and  Fruit,  are  not  essential  to  the  existence  of  the  individ 
ual,  but  their  function  is  to  maintain  the  Race.  They  are 
the  Reproductive  Organs. 


CHAPTER    IL 
THE  PRIMARY  ELEMENTS  OF  ORGANIC   STRUCTURE 

§1- 

THE    VEGETABLE    CELL. 

One  of  the  most  interesting  discoveries  that  the  micro 
scope  has  revealed,  is,  that  all  organized  matter  originates 
in  the  form  of  minute  vesicles  or  cells.  If  we  examine  by 
the  microscope  a  seed  or  an  egg,  we  find  nothing  but  a 
cell -structure — an  assemblage  of  little  globular  bags  or 
vesicles,  lying  closely  together,  and  more  or  less  filled 
with  solid  or  liquid  matters.  From  these  cells,  then,  comes 
the  frame  or  structure  of  the  plant,  or  of  the  animal.  In 
the  process  of  maturing,  the  original  vesicles  are  often 
greatly  modified  in  shape  and  appearance,  to  suit  various 
purposes;  but  still,  it  is  always  easy,  especially  in  the 
plant,  to  find  cells  of  the  same  essential  characters  as  those 
occurring  in  the  seed. 


ERSiTY 

' 
\<r 

CENTS    OF    ORGANIC    STRUCTURE.  223 

Cellular  Plants,— In  those  classes  of  vegetation  which 
depart  structurally  to  the  least  degree  from  the  seed,  and 
which  belong  to  what  are  called  the  "  lower  orders,"*  we 
find  plants  which  consist  entirely  of  cells  throughout 
all  the  stages  of  their  life,  and  indeed  many  are  known 
which  are  but  a  single  cell.  The  phenomenon  of  red  snow, 
frequently  observed  in  Alpine  and  Arctic  regions,  is  due  to 
a  microscopic  one-celled  plant  which  propagates  with  great 
rapidity,  and  gives  its  color  to  the 
surface  of  the  snow.  In  the  chem 
ist's  laboratory  it  is  often  observed 
a  that,  in  the  clearest  solutions  of 

salts,  like  the  sulphates  of  soda  and 
Fig.  27.  magnesia,  a  flocculent  mould,  some 

times  red,  sometimes  green,  most  often  white,  is  formed, 
which,  under  the  microscope,  is  seen  to  be  a  vegetation 
consisting  of  single  cells.  Brewer's  yeast,  fig.  27,  is  nothing 
more  than  a  mass  of  one  or  few-celled  plants. 

In  the  mushrooms  and  sea- weeds,  as  well  as  in  the  moulds 
that  grow  on  damp  walls,  or  upon  bread,  cheese,  etc.,  and 
in  the  brand  or  blight  which  infests  many  of  the  farmer's 
crops,  we  have  examples  of  plants  formed  exclusively  of 
cells. 

All  the  plants  of  higher  orders  we  find  likewise  to  con 
sist  chiefly  of  globular  or  angular  cells. 
All  the  growing  parts  especially,  as  the 
tips  of  the  roots,  the  leaves,  flowers,  and 
fruit,  are,  for  the  most  part,  aggregations 
of  such  minute  vesicles. 

If  we  examine  the  pulp  of  fruits,  as  that  C\ 
of  a  ripe  apple  or  tomato,  we  are  able,  by    ^      f  \ 
means  of  a  low  magnifier,  to  distinguish 
the  cells  of  which  it  almost  entirely  con 
sists.     Fig.  28  represents  a  bit  of  the  flesh  of  a  ripe  pippin, 

*  Viz. :  the  Cj-yptogams,  including  Moulds,  and  Mushrooms,  (Fungi,')  Mosses, 
Ferns,  and  Sea-Weeds,  (Algce). 


224         •  HOW    CROPS    GROW. 

magnified  50  diameters.     The  cells  mostly  cohere  together, 
but  readily  admit  of  separation. 

Structure  of  the  Cell,— By  the  aid  of  the  microscope 
it  is  possible  to  learn  something  with  regard  to  the  inter 
nal  structure  of  the  cell  itself.  Fig.  29  exhibits  the  ap 
pearance  of  a  cell  from  the  flesh  of  the  Jerusalem  Arti 
choke,  magnified  230  diameters ;  externally  the  membrane, 
or  wall  of  the  cell,  is  seen  in  section.  This  membrane  is 
filled  and  distended  by  a  transparent 
liquid,  the  sap  or  free-  water  of  vegetation. 
Within  the  cell  is  observed  a  round  body, 
b,  which  is  called  the  nucleus,  and  upon 
this  is  seen  a  smaller  nucleolus,  c.  Lining 
the  interior  of  the  cell-membrane  and 
connected  with  the  nucleus,  is  a  yellowish, 
turbid,  semi-fluid  substance  of  mucilagi 
nous  consistence,  a,  which  is  designated 
the  protoplasm,  or  formative  layer.  This,  when  more 
highly  magnified,  is  found  to  contain  a  vast  number  of 
excessively  minute  granules. 

By  the  aid  of  chemistry  the  microscopist  is  able  to  dis 
sect  these  cells,  which  are  hardly  perceptible  to  the  unas 
sisted  eye,  and  ascertain  to  a  good  degree  how  they  are 
constituted.  On  moistening  them  with  solution  of  iodine, 
and  afterward  with  sulphuric  acid,  the  outer  membrane — 
the  cell-wall — shortly  becomes  of  a  fine  blue  color.  It  is 
accordingly  cellulose,  the  only  vegetable  substance  yet 
known  which  is  made  blue  by  iodine  after,  and  only  after, 
the  action  of  sulphuric;  acid.  At  the  same  time  we  observe 
that  the  interior,  half-liquid,  protoplasm,  has  coagulated 
and  shrunk  together, — lias  therefore  separated  from  tho 
cell-wall,  and  includiii"-  with  it  the  nucleus  and  the  smallei 

9 

granules,  lies  in  the  center  of  the  ci  11  like  a  collapsed 
bladder.  It  has  also  assumed  a  deep  yellow  or  brown 
color.  If  we  moisten  one  of  these  cells  with  nitric  acid, 
the  cell-wall  is  not  affected,  but  the  liquid  penetrates  it, 


ELEMENTS  OF  ORGANIC  STRUCTURE.        225 

coagulates  the  inner  membrane,  and  colors  it  yellow, 
In  the  same  way  this  membrane  is  tinged  violet-blue 
by  chlorhydric  acid.  These  reactions  leave  no  room 
to  doubt  that  the  slimy  inner  lining  of  the  cell  is  chiefly 
an  albuminoid.  It  has  been  termed  by  vegetable  physiol 
ogists  the  protoplasm  or  formative  layer,  from  the  fact 
that  it  is  the  portion  of  the  cell  first  formed,  and  that  from 
which  the  other  parts  are  developed.  The  protoplasm  is 
not  miscible  with  or  soluble  in  water.  It  is  contractile, 
and  in  the  living  cell  is  constantly  changing  its  figure, 
while  the  granules  commonly  suspended  in  it  move  and 
circulate  as  in  a  stream  of  liquid. 

If  we  examine  the  cells  of  any  other  plant  we  find  al 
most  invariably  the  same  structure  as  above  described, 
provided  the  cells  are  young,  i.  e.,  belong  to  growing 
parts.  In  some  cases  cells  consist  only  of  protoplasm  and 
nucleus,  being  destitute  of  cell-walls  during  a  portion  or 
the  whole  of  their  existence. 

In  studying  many  of  the  maturer  parts  of  plants,  viz. : 
such  as  have  ceased  to  enlarge,  as  the  full-sized  leaf,  the 
perfectly  formed  wood,  etc.,  we  find  the  cells  do  not  cor 
respond  to  the  description  just  given.  In  external  shape, 
thickness,  and  appearance  of  the  cell-wall,  and  especially 
in  the  character  of  the  contents,  there  is  indefinite  variety. 
But  this  is  the  result  of  change  in  the  original  cells,  which, 
so  far  as  our  observations  extend,  are  always,  at  first, 
formed  closely  on  the  pattern  that  has  been  explained. 

Vegetable  Tissue. — It  does  not,  however,  usually  hap 
pen  that  the  individual  cells  of  the  higher  orders  of  plants 
admit  of  being  .obtained  separately.  They  are  attached 
together  more  or  less  firmly  by  their  outer  surfaces,  so  as 
to  form  a  coherent  mass  of  cells — a  tissue,  as  it  is  termed. 
In  the  accompanying  cut,  fig.  30,  is  shown  a  highly 
magnified  view  of  a  portion  of  a  very  thin  slice  across  a 
young  cabbage  stalk.  It  exhibits  the  outline  of  the  ir* 
10* 


226 


HOW    CROPS    GROW. 


Fig.  30. 


regular  empty  cells,  the  walls  of  which  are,  for  the  most 
part,  externally  united  and  appear  as  one,  a.  At  the  points 
indicated  by  #,  cavities  between  the  cells  are  seen,  called 
intercellular  spaces.  A  slice  across  the  potato-tuber,  (see 
fig.  52,  p.  277,)  has  a  similar  appearance,  except  that  the 

cells  are  filled  with  starch, 
and  it  would  be  scarcely 
possible  to  dissect  them 
apart ;  but  when  a  pota 
to  is  boiled,  the  starch- 
grains  swell,  and  the  cells, 
in  consequence,  separate 
from  each  other,  a  practi 
cal  result  of  which  is  to 
make  the  potato  mealy. 
A  thin  slice  of  vegetable 
ivory  (the  seed  of  Phy- 
telephas  macrocarpa)^ 
under  the  microscope,  dry  or  moistened  with  water,  pre 
sents  no  trace  of  cell-structure,  the  cells  being  united  as 
one ;  however,  upon  soaking  in  sulphuric  acid,  the  mass 
softens  and  swells,  and  the  individual  cells  are  at  once 
revealed,  their  surfaces  separating  in  six-sided  outlines. 

Form  of  Cells, — In  the  soft,  succulent  parts  of  plants, 
the  cells  lie  loosely  together,  often  with  considerable  inter 
cellular  spaces,  and  have  mostly  a  rounded  outline.  In 
denser  tissues,  the  cells  are  crowded  together  in  the  least 
possible  space,  and  hence  often  appear  six-sided  when  seen 
in  cross-section,  or  twelve-sided  if  viewed  entire.  A  piece 
of  honey-comb  is  an  excellent  illustration  of  the  appear 
ance  of  many  forms  of  vegetable  cell-tissue. 

The  pulp  of  an  orange  is  the  most  evident  example  of 
cell-tissue.  The  individual  cells  of  the  ripe  orange  may 
IK-  <-:isily  separated  from  each  other,  as  they  are  one-fourth 
of  an  inch  or  more  in  length.  !><'ing  mature  and  incapa 
ble  of  further  growth,  they  possess  neither  protoplasm  nor 


ELEMENTS    OF    ORGANIC   STRUCTURE. 


227 


nucleus,  but  are  filled  with  a  sap  or  juice  containing  citric 

acid  and  sugar. 

In  the  pHh  of  the  rush,  star-shaped  cells  are  found.  In 
common  mould  the  cells  are  long  and 
•  thread-like.  In  the  so-called  frog-spittle 
they  are  cylindrical  and  attached  end  to 
end.  In  the  bark  of  many  trees,  in  the 
stems  and  leaves  of  grasses,  they  are 
square  or  rectangular. 

Cotton-fiber,  flax  and  hemp  consist  of 
long  and  slender  cells,  fig.  31.  Wood  is 
mostly  made  up  of  elongated  cells,  tapered 
at  the -ends  and  adhering  together  by 
their  sides.  Fig.  49,  c.  A.,  p.  271. 

Each  cotton-fiber  is  a  single  cell  which  forms  an 
external  appendage  to  the  seed-vessel  of  the  cot 
ton  plant.  When  it  has  lost  its  free  water  of 
vegetation  and  become  air-dry,  i t^«f 3^  »§T^^§^, 
and  it  resembles  a  twisted  straw  /&* m  "l^o^y 
exhibits  a  portion  of  a  cotton-liber  liiirhly  magnified. 
The  flax-fiber,  from  the  inner  bark  of  the  flax- 
stem,  6,  fig.  31,  is  a  tube  of  thicker  walls  and 
smaller  bore  than  the  cotton-fiber,  and  hence  is  more  dutable  than  cot 
ton.  It  is  very  flexible,  and  even  when  crushed  or  bent  s^ort,  retains 
much  of  its  original  tenacity.  Hemp-fiber  closely  resembles  flax-fiber  in 
appearance. 

Thickening  of  the  Cell-Membrane.—  The  growth  of  the 
cell,  which,  when  young,  always  has 
a  very  delicate  outer  membrane,  often 
results  in  the  thickening  of  its  walls 
by  the  interior  deposition  of  cellu 
lose  and  lignin.  This  thickening  may 
take  place  regularly  and  uniform 
ly,  or  interruptedly.  The  flax-fiber, 
6,  fig.  31,  is  an  example  of  nearly 
uniform  thickening.  The  irregular 
deposition  of  cellulose  is  shown  in 

fig.  32,  which  exhibits  a  section  from  Fig.  32. 

the  seeds  (cotyledons)  of  the  com 
mon  nasturtium,  (Tropceolum  majuii).     The  original  membrane  is  coated 
interiorly  with  several  distinct  and  successively-formed  linings,  which 
are  not  continuous,  but  are  irregularly  developed.     Seen  in  section,  the 


228  HOW  CHOPS  GKOW. 

thickening  has  a  waved  outline,  and  at  points,  the  original  cell-mem 
brane  is  bare.  Were  these  cells  viewed  entire,  we  should  see  at  thesa 
points,  on  the  exterior  of  the  cell,  dots  or  circles  appearing  like  orific<»y 
but  being  simply  the  unthickened  portions  of  the  cell-wall.  The  cells 
in  fig.  32  exhibit  each  a  central  nucleus  surrounded  by  grains  of  aleurone. 

Cell  Contents.  —  Besides  the  protoplasm  and  nucleus, 
the  cell  usually  contains  a  variety  of  bodies,  which  have 
been,  indeed,  noticed  already  as  ingredients  of  the  plant, 
but  which  may  be  here  recapitulated.  Many  cells  are  al 
together  empty,  and  consist  of  nothing  but  the  cell-wall. 
Such  are  found  in  the  bark  or  epidermis  of  most  plants, 
and  often  in  the  pith,  and  although  they  remain  connected 
with  the  actually  living  parts,  they  have  no  proper  life  in 
themselves. 

All  living  or  active  cells  are  distended  with  liquid.  This 
consists  of  water,  which  holds  in  solution  gum,  dextrin, 
inulin,  the  sugars,  organic  acids,  and  other  less  important 
vegetable  principles,  together  with  various  salts,  and 
constitutes  the  sap  of  the  plant.  In  oil-plants,  droplets  of 
oil  occupy  certain  cells,  fig.  17,  p.  90 ;  while  in  numerous 
kinds  of  vegetation,  colored  and  milky  juices  are  found  in 
certain  spaces  or  channels  between  the  cells. 

The  water  of  the  cell  comes  from  the  soil,  as  we  shall 
hereafter  see.  The  matters,  which  are  dissolved  in  the  sap 
or  juices  of  the  plant,  together  with  the  semi-solid  proto 
plasm,  undergo  transformations  resulting  in  the  production 
of  solid  substances.  By  observing  the  various  parts  of  a 
plant  at  the  successive  stages  of  its  development,  under 
the  microscope,  we  are  able  to  trace  within  the  cells  the 
formation  and  growth  of  starch-grains,  of  crystalloid  and 
granular  bodies  consisting  chiefly  of  vegetable  casein,  and 
of  the  various  matters  which  give  color  to  leaves  and 
flowers. 

The  circumstances  under  which  a  cell  developes  deter 
mine  the  character  of  its  contents,  according  to  laws  that 
are  hidden  from  our  knowledge.  The  outer  cells  of  the 
potato-tuber  are  incrusted  with  corky  matter,  the  innei 


ELEMENTS    OP    ORGANIC   STRUCTURE. 

ones,  most  of  them,  are  occupied  entirely  with  starch,  fig. 
5:2,  p.  277.  In  oats,  wheat,  and  other  cereals,  we  find,  just 
within  the  empty  cells  of  the  skin  or  epidermis  of  the 
grain,  a  few  layers  of  cells  that  contain  scarcely  anything 
but  albuminoids,  with  a  little  fat ;  while  the  interior  cells 
are  chiefly  filled  with  starch ;  fig.  18,  p.  106. 

Transformations  in  Cell  Contents, — The  same  cell  may 
exhibit  a  great  variety  of  aspect  and  contents  at  different 
periods  of  growth.  This  is  especially  to  be  observed  in 
the  seed  while  developing  on  the  mother  plant.  Hartig 
has  traced  these  changes  in  numerous  plants  under  the  mi 
croscope.  According  to  this  observer,  the  cell-contents  of 
the  seed  (cotyledons)  of  the  common  nasturtium,  (Trop- 
ceolum  majus,)  run  through  the  following  metamorphoses. 
Up  to  a  certain  stage  in  its  development  the  interior  of 
the  cells  are  nearly  devoid  of  recognizable  solid  matters, 
other  than  the  nucleus  and  the  adhering  protoplasm. 
Shortly,  as  the  growth  of  the  seed  advances,  green  grains 
of  chlorophyll  make  their  appearance  upon  the  nucleus, 
completely  covering  it  from  view.  At  a  later  stage,  these 
grains,  which  have  enlarged  and  multiplied,  are  seen  to 
have  mostly  become  detached  from  the  nucleus,  and  lie 
near  to  and  in  contact  with  the  cell-wall.  Again,  in  a 
short  time  the  grains  have  lost  their  green  color  and  have 
assumed,  both  as  regards  appearance  and  deportment  with 
iodine,  all  the  characters  of  starch.  Subsequently,  as  the 
seed  hardens  and  becomes  firmer  in  its  tissues,  the  micro 
scope  reveals  that  the  starch-grains,  which  were  situated 
near  the  cell-wall,  have  vanished,  while  the  cell-wall  itself 
has  thickened  inwardly — the  starch  having  been  convert 
ed  into  cellulose.  Again,  later,  the  nucleus,  about  which, 
in  the  meantime,  more  starch-grains  have  been  formed, 
undergoes  a  change  and  disappears ;  then  the  starch-grains, 
some  of  which  have  enlarged  while  others  have  vanished, 
are  found  to  be  imbedded  in  a  pasty  matter,  which  has  the 
reactions  of  an  albuminoid.  From  this  time  on,  the 


230 


UOW    CROPS    GROW. 


starch-grains  are  gradually  converted  from  their  surfaces 
inwardly  into  smaller  grains  of  aleurone,  which,  finally, 
when  the  seed  is  mature,  completely  occupy  the  cells. 

In  the  sprouting  of  the  seed  similar  changes  occur,  but 
in  reversed  order.  The  nucleus  reappears,  the  aleurone  dis 
solves,  and  even  the  cellulose  stratified  upon  the  interior 
of  the  cell,  fig.  32,  wastes  away  and  is  converted  into 
soluble  food  (sugar?)  for  the  seedling. 

The  Dimensions  of  Vegetable  Cells  are  very  various. 
A  creeping  marine  plant  is  known — the  Caulerpa prolifera, 


Fig.  83. 

fig.  33, — which  consists  of  a  single  cell,  though  it  is  often 
a  foot  in  length,  and  is  branched  with  what  have  the  ap- 
jH'arance  of  leaves  and  roots.  The  pulp  of  the  orange  con 
sists  of  cells  which  are  one-quarter  of  an  inch  or  more  in 
diameter.  Every  fiber  of  cotton  is  a  single  cell.  In  most 


ELEMENTS    OF    ORGANIC    STRUCTURE.  231 

cases,  however,  the  cells  of  plants  are  so  small  as  to  re 
quire  a  powerful  microscope  to  distinguish  them, — are,  in 
fact,  no  more  than  l-1200th  to  l-200th  of  an  inch  in  diam 
eter  ;  many  are  vastly  smaller. 

Growth. — The  growth  of  a  plant  is  nothing  more  than 
the  aggregate  result  of  the  enlargement  and  multiplication 
of  the  cells  which  compose  it.  In  most  cases  the  cells  at-, 
tain  their  full  size  in  a  short  time.  The  continuous  growth 
of  plants  depends,  then,  chiefly  on  the  constant  and  rapid 
formation  of  new  cells. 

Cell-multiplication. — The  young  and  active  cell  always 
contains  a  nucleus,  (fig.  34,  b.)  Such  a  cell  may  produce 
a  new  cell  by  division.  In  this  process 
the  nucleus,  from  which  all  cell-growth 
appears  to  originate,  is  observed  to  re 
solve  itself  into  two  parts,  then  the 
protoplasm,  «,  begins  to  contract  or  in 
fold  across  the  cell  in  a  line  correspond 
ing  with  the  division  of  the  nucleus,  until 
the  opposite  infolded  edges  meet — like 
the  skin  of  a  sausage  where  a  string  is 
tightly  tied  around  it, — thus  separating  the  two  nuclei  and 
inclosing  each  within  its  new  cell,  which  is  completed  by 
a  further  external  growth  of  cellulose. 

In  one-celled  plants,  like  yeast,  (fig.  35,)  the  new  cells 
thus  formed,  bud  out  from  the  side 
of  the  parent-cell,  and  before  they 
obtain  full  size  become  entirely 
detached  from  it,  or,  as  in  higher 
plants,  the  new  cells  remain  adher 
ing  to  the  old,  forming  a  tissue.  FiS-  35- 

In  free  cell-formation  nuclei  are  observed  to  develope 
in  the  protoplasm  of  a  parent  cell,  which  enlarge,  surround 
themselves  with  their  own  protoplasm  and  cell-membrane, 
and  by  the  resorption  or  death  of  the  parent  cell  become 
independent  of  the  latter. 


232  HOW   CROPS 

The  rapidity  with  which  the  vegetable  cells  may  multi 
ply  and  grow  is  illustrated  by  many  familiar  facts.  The 
most  striking  cases  of  quick  growth  are  met  with  in  the 
mushroom  family.  Many  will  recollect  having  seen  on  the 
morning  of  a  June  day;  huge  puff-balls,  some  as  large  as  a 
peck  measure,  on  the  surface  of  a  moist  meadow,  where 
the  day  before  nothing  of  the  kind  was  noticed.  In  such 
sudden  growth  it  has  been  estimated  that  the  cells  are 
produced  at  the  rate  of  three  or  four  hundred  millions  per 
hour. 

Permeability  of  Cells  to  Liquids. — Although  the  high 
est  magnifying  power  that  can  be  brought  to  bear  upon 
the  membranes  of  the  vegetable  cell  foils  to  reveal  any 
apertures  in  them, — they  being,  so  far  as  the  best-assisted 
vision  is  concerned,  completely  continuous  and  imperforate, 
— they  are  nevertheless  readily  permeable  to  liquids. 
This  fact  may  be  elegantly  shown  by  placing  a  delicate 
slice  from  a  potato-tuber,  immersed  in  water,  under  the 
microscope,  and  then  bringing  a  drop  of  solution  of  iodine 
in  contact  with  it.  Instantly  this  reagent  penetrates  the 
walls  of  the  unbroken  cells  without  perceptibly  affecting 
their  appearance,  and  being  absorbed  by  the  starch-grains, 
at  once  colors  them  intensely  purplish- blue.  The  particles 
of  which  the  cell-walls  and  their  contents  are  composed, 
must  be  separated  from  each  other  by  distances  greater 
than  the  diameter  of  the  particles  of  water  or  of  other 
liquid  matters  which  thus  permeate  the  cells. 

§2. 
THE  VEGETABLE  TISSUES. 

As  already  stated,  the  cells  of  the  higher  kinds  of  plants 
are  united  together  more  or  less  firmly,  and  thus  consti< 
tute  what  are  known  as  VEGETABLE  TISSUES.  Of  these, 
a  large  number  have  been  distinguished  by  vegetable  anal- 


ELEMENTS    OF    ORGANIC    STRUCTURE.  3 

omists,  the  distinctions  being  based  either  ou  peculiarities 
of  form  or  of  function.  For  our  purposes  it  will  be  neces 
sary  to  define  but  a  few  varieties,  viz ,  Cellular  Tissue, 
Woody  Tissue,  JBast- Tissue,  and  Vascular  Tissue. 

Cellular  or  Cell-Tissue  is  the  simplest  of  all,  being 
a  mere  aggregation  of  globular  or  polyhedral  cells  whose 
walls  are  in  close  adhesion,  and  whose  juices  commingle 
more  or  less  in  virtue  of  this  connection.  Cellular  tissue 
is  the  groundwork  of  all  vegetable  structure,  being  the 
only  form  of  tissue  in  the  simpler  kinds  of  plants,  and 
that  out  of  which  all  the  others  are  developed.  The 
term  parenchyma  is  synonymous  with  cell-tissue. 

Wood-Tissue,  in  its  simplest  form,  consists  of  cells  that 
are  several  or  many  times  as  long  as  they  are  broad,  and 
that  taper  at  each  end  to  a  point.  These  spindle-shaped 
cells  cohere  firmly  together  by  their  sides,  and  "  break 
joints "  by  overlapping  each  other,  in  this  way  forming 
the  tough  fibers  of  wood.  Wood-cells  are  often  more 
or  less  thickened  in  their  walls  by  depositions  of  cellulose, 
lignin,  and  coloring  matters,  according  to  their  age  and 
position,  and  are  sometimes  dotted  and  perforated,  as  will 
be  explained  hereafter,  fig.  53,  p.  278. 

Bast-Tissue  is  made  up  of  long  and  slender  cells,  similar 
to  those  of  wood-tissue,  but  commonly  more  delicate  and 
flexible.  The  name  is  derived  from  the  occurrence  of  this 
tissue  in  the  bast,  or  inner  bark.  Linen,  hemp,  and  all 
textile  materials  of  vegetable  origin,  cotton  excepted,  con. 
gist  of  bast-fibers.  Bast-cells  occupy  a  place  in  rind,  corres 
ponding  to  that  held  by  wood-cells  in  the  interior  of  tht 
stem,  fig.  49,  p.  271 .  Prosenchyma  is  a  name  applied  to 
all  tissues  composed  of  elongated  cells,  like  those  of  wood 
and  bast.  Parenchyma  and  prosenchyma  insensibly  shade 
iato  each  other. 

Vascular  Tissue  is  the  term  applied  to  those  unbranched 
Tube*  and  Ducts  which  are  found  in  all  the  higher  orders 


234  HOW   CHOPS    GEOW. 

of  plants,  interpenetrating  the  cellular  tissue.  There  are 
several  varieties  of  ducts,  viz.,  dotted  ducts,  ringed  or  an 
nular  ducts,  and  spiral  ducts,  of  which  illustrations  will 
be  given  when  the  minute  structure  of  the  stem  comes 
under  notice,  fig.  49,  p.  271. 

The  formation  of  vascular  tissue  takes  place  by  a  simple 
alteration  in  cellular  tissue.  A  longitudinal  series  of  ad 
hering  cells  represents  a  tube,  save  that  the  bore  is  ob 
structed  with  numerous  transverse  partitions.  By  the 
removal  or  perforation  of  these  partitions  a  tube  is  devel 
oped.  This  removal  or  perforation  actually  takes  place 
in  the  living  plant  by  a  process  of  absorption. 


CHAPTER  in. 
THE  VEGETATIVE  ORGANS  OF  PLANTS. 

§1- 
THE  ROOT. 


The  ROOTS  of  plants,  with  few  exceptions,  from  the  first 
moment  of  their  development  grow  downward,  in  obe 
dience  to  the  force  of  gravitation.  In  general,  they  require 
a  moist  medium.  They  will  form  in  water  or  in  moist  cot 
ton,  and  in  many  cases  originate  from  branches,  or  even 
leaves,  when  these  parts  of  the  plant  are  buried  in  the 
earth  or  immersed  in  water.  It  cannot  be  assumed  that 
they  seek  to  avoid  the  light,  because  they  may  attain  a 
full  development  without  being  kept  in  darkness.  Tha 


THE    VEGETATIVE    ORGANS    OF   PLANTS.  235 

action  of  light  upon  them,  however,  appears  to  be  unfavor 
able  to  their  functions. 

The  Growth  Of  Roots  occurs  mostly  by  lengthening, 
and  very  little  or  very  slowly  by  increase  of  thickness. 
The  lengthening  is  chiefly  manifested  toward  the  outer 
extremities  of  the  roots,  as  was  neatly  demonstrated  by 
Wigand,  who  divided  the  young  root  of  a  sprouted  pea 
into  four  equal  parts  by  ink-marks.  After  three  days,  the 
first  two  divisions  next  the  seed  had  scarcely  lengthened 
at  all,  while  the  third  was  double,  and  the  fourth  eight 
times  its  previous  length.  Olilerts  made  precisely  similar 
observations  on  the  roots  of  various  kinds  of  plants.  The 
growth  is  confined  to  a  space  of  about  l\6  of  an  inch  from 
the  tip.  (Linnea,  1837,  pp.  609-631.)  This  peculiarity 
adapts  the  roots  to  extend  through  the  soil  in  all  direc 
tions,  and  to  occupy  its  smallest  pores,  or  rifts.  It  le 
likewise  the  reason  that  a  root,  which  has  been  cut  off  rn 
transplanting  or  otherwise,  never  afterwards  extends  in 
length. 

Although  the  older  parts  of  the  roots  of  trees  and  of 
the  so-called  root-crops  acquire  a  considerable  diameter, 
the  roots  by  which  a  plant  feeds  are  usually  thread-like 
and  often  exceedingly  slender. 

Spongioles, — The  tips  of  the  rootlets  have  been  termed 
spongioles,  or  spongelets,  from  the  idea  that  their  texture 
adapts  them  especially  to  collect  food  for  the  plant,  and 
that  the  absorption  of  matters  from  the  soil  goes  on  exclu 
sively  through  them.  In  this  sense,  spongioles  do  not 
exist.  The  real  living  apex  of  the  root  is  not,  in  fact,  the 
outmost  extremity,  but  is  situated  a  little  within  that 
point. 

Root-Cap. — The  extreme  end  of  the  root  usually  consists 
of  cells  that  have  become  loosened  and  in  part  detached 
from  the  proper  cell-tissue  of  the  root,  which,  therefore, 
ihortly  perish,  and  serve  merely  as  an  elastic  cushion  or 


236 


HOW    CROP,}    GltO'.V. 


cap  to  protect  the  true  termination  or  living  point  of  the 

root  in  its  act  of  penetrating  the  soil.  Fig.  06  represents 
a  magnified  section  of  part  of  a 
barley  root,  showing  the  loose 
cells  which  slough  off  from  the  tip. 
These  cells  are  filled  with  air  in 
stead  of  sap. 
A  most  strik 
ing  illustra 
tion  of  the 
root  -  cap  is 
furnished  by 
the  air-roots 
of  the  so- 
called  Screw 
Piue,  (Pai  teta 
nus  odorutis- 

simus^)  exhibited   in    natural    dimen 
sions,  in  fig.  37.     These  air-roots  issue 

from  the  stem  above  the  ground,  and, 

growing   downwards,  enter  the  soil, 

and  become  roots  in  the  ordinary  sense. 
When   fresh,  the  diameter  of  the 

root  is  quite  uniform,  but  the  parts 

above  the  root-cap  shrink  on   drying, 

while  the  root-cap  itself  retains  nearly 

its    original    dimensions,    and    thus 

reveals  its  different  structure. 
Distinction    between    Root    and 

Stem, — Not  all  the  subterranean  parts 

of  the    plant  are  roots  in   a  proper 

sense,  although  commonly  spoken  of  as  such.     The  tubers 

of  the  potato  and  artichoke,  and  the  fleshy  horizontal  parts 

of  the  sucd-llaLT  and  pepper-root,  are  merely  underground 

stems,  of  which  many  varieties  exist. 

These  and  all  other  stems  are  easily  distinguished  from 


Fiir.  37. 


THE   VEGETATIVE    ORGANS    OF   PLANTS.  237 

true  roots  by  the  imbricated  buds,  of  which  indications 
may  usually  be  found  on  their  surfaces,  e.  g.,  the  eyes  of 
the  potato-tuber.  The  side  or  secondary  roots  are  indeed 
marked  in  their  earliest  stages  by  a  protuberance  on  the 
primary  root,  but  these  have  nothing  in  common  with  the 
structure  of  true  buds.  The  onion-bulb  is  itself  a  fleshy 
bud,  as  will  be  noticed  subsequently.  The  true  roots  of 
the  onion  are  the  fibers  which  issue  from  the  base  of  the 
bulb.  The  roots  of  many  plants  exhibit  no  buds  upon  their 
surface,  and  are  incapable  of  developing  them  under  any 
conditions.  Other  plants  may  produce  them  when  cut  off 
from  the  parent  plant  during  the  growing  season.  Such 
are  the  plum,  apple,  poplar,  and  hawthorn.  The  roots  of 
the  former  perish  if  deprived  of  connection  with  the  stem 
and  leaves.  The  latter  may  strike  out  new  stems  and 
leaves  for  themselves.  Plants  like  the  plum  are,  therefore, 
capable  of  propagation  by  root-cuttings,  i.  e.,  by  placing 
pieces  of  their  roots  in  warm  and  moist  earth. 

Tap-Roots^ — All  plants  whose  seeds  readily  divide  into 
two  parts,  and  whose  stems  increase  externally  by  addi 
tion  of  new  rings  of  growth — the  so-called  dicotyledonous 
plants,  or  JExogens,  have,  at  first,  a  single  descending  axis, 
the  tap-root,  which  penetrates  vertically  into  the  ground. 
From  this  central  tap-root,  lateral  roots  branch  out  more 
or  less  regularly,  and  these  lateral  roots  subdivide  again 
and  again.  In  many  cases,  especially  at  first,  the  lateral 
roots  issue  from  the  tap-root  with  great  order  and  regu 
larity,  as  much  as  is  seen  in  the  branches  of  the  stem  of  a 
fir-tree  or  of  a  young  grape  vine.  In  older  plants,  this 
order  is  lost,  because  the  soil  opposes  mechanical  hindrances 
to  regular  development.  In  many  cases  the  tap-root  grows 
to  a  great  length,  and  forms  the  most  striking  feature  or' 
the  radication  of  the  plant.  In  others  it  enters  the  ground 
but  a  little  way,  or  is  surpassed  in  extent  by  its  side 
branches.  The  tap-root  is  conspicuous  in  the  Canada 
thistle,  dock,  (Rttmex^  and  in  seedling  fruit  trees.  The 


238  HOW    CROPS   GROW. 

upper  portion  of  the  tap-root  of  the  beet,  turnip,  carrot, 
and  radish,  expands  under  cultivation,  and  becomes  a 
fleshy,  nutritive  mass,  in  which  lies  the  value  of  these 
plants  for  agriculture.  The  lateral  roots  of  other  plants, 
as  of  the  dahlia  and  sweet  potato,  swell  out  at  their  ex 
tremities  to  tubers. 

Crown  Roots. — Monocotyledonons plants9or  Endogens, 
i.  e.,  plants  whose  seeds  do  not  split  with  ease  into  two 
nearly  equal  parts,  and  whose  stems  increase  by  inside 
growth,  such  as  the  cereals,  grasses,  lilies,  palms,  etc., 
have  no  single  tap-root,  but  produce  crown  roots,  i.  e., 
a  number  of  roots  issue  at  once  in  quick  succession  from 
the  base  of  the  stem.  This  is  strikingly  seen  in  the  onion 
and  hyacinth,  as  well  as  in  maize, 

Rootlets* — This  term  we  apply  to  the  slender  roots, 
usually  not  larger  than  a  knitting  needle,  and  but  a  few 
inches  long,  which  are  formed  last  in  the  order  of  growth, 
and  correspond  to  the  larger  roots  as  twigs  correspond  to 
the  branches  of  the  stem. 

THE  OFFICES  OF  THE  ROOT  are  threefold : 

1 .  To  fix  the  plant  in  the  earth  and  maintain  it,  in  most 
cases,  in  an  upright  position. 

2.  To  absorb  nutriment  from  the  soil  for  the  growth  of 
the  entire  plant,  and, 

3.  In  case  of  many  plants,  especially  of  those  whose 
terms  of  life  extend  through  several  or  many  years,  to 
Berve  as  a  store-house  for  the  future  use  of  the  plant. 

1,  The  Firmness  with  which  a  Plant  is  fixed  in  the 
Ground  depends  upon  the  nature  of  its  roots.  It  is  easy 
to  lift  an  onion  from  the  soil,  a  carrot  requires  much  more 
force,  while  a  dock  may  resist  the  full  strength  of  a  pow 
erful  man.  A  small  beech  or  seedling  apple  tree,  which 
has  a  tap-root,  withstands  the  force  of  a  wind  that  would 
pr<  >st  nil  t  •  a  maize-plant  or  a  poplar,which  has  only  side  roots. 
In  the  nursery  it  is  the  custom  to  cut  off  the  tap-root  of 


THE   VEGETATIVE    ORGANS    OF   PLANTS.  289 

apple,  peach,  and  other  trees,  when  very  young,  in  order 
that  they  may  be  readily  and  safely  transplanted  as  occa 
sion  shall  require.  The  depth  and  character  of  the  soil, 
however,  to  a  certain  degree  influence  the  extent  of  the 
roots  and  the  tenacity  of  their  hold.  The  roots  of  maize, 
which  in  a  rich  and  tenacious  earth  extend  but  two  or  three 
feet,  have  been  traced  to  a  length  of  ten  or  even  fifteen 
feet  in  a  light,  sandy  soil.  The  roots  of  clover,  and  espe 
cially  those  of  lucern,  extend  very  deeply  into  the  soil, 
and  the  latter  acquire  in  some  cases  a  length  of  30  feet. 
The  roots  of  the  ash  have  been  known  as  many  as  95  feet 
long.  (Jour.  Roy.  Ag.  Soc.,  VI,  p.  342.) 

2.  ^Root-absorption. — The  Office  of  absorbing  Plant 
Food  froijfi  the  Soil  is  one  of  the  utmost  importance,  and 
one  for  which  the  root  is  most  wisely  adapted  by  the  fol 
lowing  particulars,  viz.: 

a,  The  Delicacy  of  its  Structure,  especially  that  of  the 
newer  portions,  the  cells  of  which  are  very  soft  and  absor 
bent,  as  may  be  readily  shown  by  immersing  a  young 
seedling  bean  in  solution  of  indigo,  when  the  roots  shortly 
acquire  a  blue  color  from  imbibing  the  liquid,  while  the 
stem,  a  portion  of  which  in  this  plant  extends  below  the 
seed,  is  for  a  considerable  time  unaltered. 

It  is  a  common  but  erroneous  idea  that  absorption  from 
the  soil  can  only  take  place  through  the  ends  of  the  roots 
— through  the  so-called  spongioles.  On  the  contrary,  the 
extreme  tips  of  the  rootlets  cannot  take  up  liquids  at  alL 
(Ohlerts,  loc.  cit.,  see  p.  249.)  All  other  parts  of  the  roots 
which  are  still  young  and  delicate  in  surface-texture,  are 
constantly  active  in  the  work  of  imbibing  nutriment  from 
the  soiL 

In  most  perennial  plants,  indeed,  the  larger  branches  of 
the  roots  become  after  a  time  coated  with  a  corky  or  oth 
erwise  nearly  impervious  cuticle,  and  the  function  of  ab 
sorption  is  then  transferred  to  the  rootlets.  This  is  demon 


240  HOW   CROPS   GROW. 

strated  by  placing  the  old,  brown -colored  roots  of  a  plant 
in  water,  but  keeping  the  delicate  and  unindnrated  ex 
tremities  above  the  liquid.  Thus  situated,  the  plant  with 
ers  nearly  as  soon  as  if  its  root-surface  were  all  exposed  to 
the  air. 

b.  Its  Rapid  Extension  in  Length,  and  the  vast  Sur 
face  which  it  puts  in  contact  with  the  soil,  further  adapts 
the  root  to  the  work  of  collecting  food.  The  length  of 
roots  in  a  direct  line  from  the  point  of  their  origin  is  not,  in 
deed,  a  criterion  by  which  to  judge  of  the  efficiency  where 
with  the  plant  to  which  they  belong  is  nourished ;  for 
two  plants  may  be  equally  flourishing — be  equally  fed  by  • 
their  roots — when  these  organs,  in  one  case,  reach  but  one 
foot,  and  in  the  other  extend  two  feet  from  the  stein  to 
which  they  are  attached.  In  one  case,  the  roots  would  be 
fewer  and  longer;  in  the  other,  shorter  and  more  numer 
ous.  Their  aggregate  length,  or,  more  correctly,  the  ag 
gregate  absorbing  surface,  would  be  nearly  the  same  in 
both. 

The  Medium  in  which  Roots  Grow  has  a  great  influence 
on  their  extension.  When  they  are  situated  in  concen 
trated  solutions,  or  in  a  very  fertile  soil,  they  are  short, 
and  numerously  branched.  Where  their  food  is  sparse, 
they  are  attenuated,  and  bear  a  comparatively  small  num 
ber  of  rootlets.  Illustrations  of  the  former  condition  are 
often  seen.  Bones  and  masses  of  manure  are  not  infre 
quently  found,  completely  covered  and  penetrated  by  a 
fleece  of  stout  roots.  On  the  other  hand,  the  roots  which 
grow  in  poor,  sandy  soils,  are  very  long  and  slender. 

Nobbe  has  described  some  experiments  which  com 
pletely  establish  the  point  under  notice.  ( Vs.  St.,  IV,  p. 
212.)  lie  allowed  maize  to  grow  in  a  poor  clay  soil,  con 
tained  in  glass  cylinders,  each  vessel  having  in  it  a  quan 
tity  of  a  fertilizing  mixture  disposed  in  some  peculiar  man- 
wr  for  the  purpose  of  observing  its  influence  on  the  roots. 
When  the  plants  had  been  nearly  four  months  in  growth, 


THE    VEGETATIVE    ORGANS    OF   PLANTS.  241 

• 

the  vessels  were  placed  in  water  until  the  earth  was  soft 
ened,  so  that  by  gentle  agitation  it  could  be  completely 
removed  from  the  roots.  The  .atter,  on  being  suspended 
in  a  glass  vessel  of  water,  assumed  nearly  the  position  they 
had  occupied  in  the  soil,  and  it  was  observed  that  where 
the  fertilizer  had  been  thoroughly  mixed  with  the  soil, 
the  roots  uniformly  occupied  its  entire  mass. 

Where  the  fertilizer  had  been  placed  in  a  horizontal 
layer  at  the  depth  of  about  one  inch,  the  roots  at  that 
depth  formed  a  mat  of  the  finest  fibers.  Where  the  fer 
tilizer  was  situated  in  a  horizontal  layer  at  half  the  depth 
of  the  vessel,  just  there  the  root-system  was  spheroidally 
expanded.  In  the  cylinders  where  the  fertilizer  formed  a 
vertical  layer  on  the  interior  walls,  the  external  roots  were 
developed  in  numberless  ramifications,  while  the  interior 
roots  were  comparatively  unbranched.  In  pots,  where 
the  fertilizer  was  disposed  as  a  central  vertical  core,  the 
inner  roots  were  far  more  greatly  developed  than  the  outer 
ones.  Finally,  in  a  vessel  where  the  fertilizer  was  placed 
in  a  horizontal  layer  at  the  bottom,  the  roots  extended 
through  the  soil,  as  attenuated  and  slightly  branched 
fibers,  until  they  came  in  contact  with  the  lower  stratum, 
where  they  greatly  increased  and  ramified.  In  all  cases, 
the  principal  development  of  the  roots  occurred  in  the 
immediate  vicinity  of  the  material  which  could  furnish 
them  with  nutriment. 

It  has  often  been  observed  that  a  plant  whose  aerial 
branches  are  symmetrically  disposed  about  its  stem,  has 
the  larger  share  of  its  roots  on  one  side,  and  again  we  find 
roots  which  are  thick  with  rootlets  on  one  side,  and  nearly 
devoid  of  them  on  the  other. 

Apparent  Search  for  Food. — It  would  almost  appear, 
on  superficial  consideration,  that  roots  are  endowed  with  a 
kind  of  intelligent  instinct,  for  they  seem  to  go  in  search 
of  nutriment. 
11 


242  HOW    CROPS    GROW. 

The  roots  of  a  plant  make  their  first  issue  independently 
of  the  nutritive  matters  that  may  exist  in  their  neighbor 
hood.  They  arc  organized  and  put  forth  from  the  plant 
itself,  no  matter  how  fertile  or  sterile  the  medium  that 
surrounds  them.  When  they  attain  a  certain  develop 
ment,  they  are  ready  to  exercise  their  office  of  collecting 
food.  If  food  be  at  hand,  they  absorb  it,  and,  together 
with  the  entire  plant,  are  nourished  by  it — they  grow  in 
consequence.  The  more  abundant  the  food,  the  better  they 
are  nourished,  and  the  more  they  multiply.  The  plant 
sends  out  rootlets  in  all  directions;  those  which  come  in 
contact  with  food,  live,  enlarge,  and  ramify;  those  which 
find  no  nourishment,  remain  undeveloped  or  perish. 

The  Quantity  Of  Roots  actually  attached  to  any  plant 
is  usually  far  greater  than  can  be  estimated  by  roughly 
lifting  them  from  the  soil.  To  extricate  the  roots  of 
wheat  or  clover,  for  example,  from  the  earth,  completely, 
is  a  matter  of  no  little  difficulty.  Schubart  has  made  the 
most  satisfactory  observations  we  possess  on  the  roots  of 
several  important  crops,  growing  in  the  field.  He  sepa 
rated  them  from  the  soil  by  the  following  expedient:  An 
excavation  was  made  in  the  field  to  the  depth  of  6  feet,  and 
a  stream  of  water  was  directed  against  the  vertical  wall 
of  soil  until  it  was  washed  away,  so  that  the  roots  of  the 
plants  GTOwincr  in  it  were  laid  bare.  The  roots  thus  ex- 

r^  o  o 

posed  in  a  field  of  rye,  in  one  of  beans,  and  in  a  bed  of  gar 
den  peas*,  presented  the  appearance  of  a  mat  or  felt  of  white 
fibers,  to  a  depth  of  about  4  feet  from  the  surface  of  the 
ground.  The  roots  of  winter  wheat  he  observed  as  deep 
as  7  feet,  in  a  light  subsoil,  forty-seven  days  after  sowing. 
The  depth  of  the  roots  of  winter  wheat,  winter  rye,  and 
winter  col/a,  as  well  as  of  clover,  was  J5-4  flvt.  The  roots 
of  clover,  one  year  old,  were  3^-  feet  long,  those  of  two- 
year-old  clover  but  4  inches  longer.  The  quantity  of  roots 
in  per  cent  of  the  entire  plant  in  the  dry  state  was  found 
to  be  as  follows.  (Chem.  Ackersmann,  I,  p.  193.) 


THE  VEGETATIVE  ORGANS  OF  PLANTS.       243 

Winter  wheat— examined  last  of  April 40U|« 

"  "  "  "  "May 22" 

'•  rye  "  u  "  April .34" 

Peas  examined  four  weeks  after  sowing1 44  " 

"  "  at  tlie  time  of  blossom 24" 

Hellriegel  has  likewise  studied  the  radication  of  barley 
and  oats,  (Hoff,  Jahresbe/ieht,  1864,  .p.  106.)  He  raised 
plants  in  large  glass  pots,  and  separated  their  roots  from 
the  soil  by  careful  washing  with  water.  He  observed  that 
directly  from  the  base  of  the  stem  20  to  30  roots  branch 
oif  sideways  and  downward.  These  roots,  at  their  point 
.of  issue,  have  a  diameter  of '  |25  of  an  inch,  but  a  little 
lower  the  diameter  diminishes  to  about  l|100  of  an  inch. 
Retaining  this  diameter,  they  pass  downward,  dividing 
and  branching  to  a  certain  depth.  From  these  main  roots 
branch  out  innumerable  side  roots,  which  branch  again, 
and  so  on,  filling  every  crevice  and  pore  of  the  soil. 

To  ascertain  the  total  length  of  root,  Hellriegel  weighed 
and  ascertained  the  length  of  selected  average  portions. 
Weighing  then  the  entire  root-system,  he  calculated  the 
entire  length.  He  estimated  the  length  of  the  roots  of  a 
vigorous  barley  plant  at  128  feet,  that  of  an  oat  plant  at 
150  feet.*  He  found  that  a  small  bulk  of  good  fine  soiJ 
sufficed  for  this  development ;  1 140  cub.  foot,  (4  *  4  *  23 14  in.,) 
answered  for  a  barley  plant ;  l  |3a  cub.  foot  for  an  oat  plant, 
in  these  experiments. 

Hellriegel  observed  also  that  the  quality  of  the  soil  in 
fluenced  the  development.  In  rich,  porous,  garden-soil,  a 
barley  plant  produced  128  feet  of  roots,  but  in  a  coarse 
grained,  compact w  soil,  a  similar  p'ant  had  but  80  feet  of 
roots. 

Root-Hairs. — The  real  absorbent  surface  of  roots  is,  in 
most  cases,  not  to  be  appreciated  without  microscopic  aid. 
The  roots  of  the  onion  and  of  many  other  bulbs,  i.  e.,  the 
fibers  which  issue  from  the  base  of  the  bulbs,  are  perfectly 

•  Rheuish  fecv. 


241 


HOW    CROPS    GROW. 


smooth  and  unbranched  throughout  their  entire  length. 
Other  agricultural  plants  have  roots 
which  are  not  only  visibly  branched, 
but  whose  finest  fibers  are  more  or 
less  thickly  covered  with  minute 
.  hairs,  scarcely  perceptible  to  the  un 
assisted  eye.  These  root-hairs  consist 
always  of  tubular  elongations  of  tho 
external  root-cells,  and  through  them 
the  actual  root-surface  exposed  to  the 
soil  becomes  something  almost  incal 
culable.  The  accompanying  figures 
illustrate  the  appearance  of  root-hairs. 
Fig  38  represents  a  young,  seed 
ling,  mustard-plant.  A  is  the  plant, 
as  carefully  lifted  from  the  sand  in 
which  it  grew,  and  J5  the  same  plant, 
freed  from  adhering  soil  by  agitating 
in  water.  The  entire  root,  save  the 
tip,  is  thickly  beset  with  hairs.  In 
fig.  39  a  minute  portion  of  a  barley- 
root  is  shown  highly  magnified.  The 
hairs  are  seen  to  be  slender  tubes  that 
proceed  from,  and  form  part  of,  the 

outer  cells  of  the  root. 

The    older     roots     lose    their 

hairs,  and  suffer  a  thickening  of 

the  outermost  layer  of  cells  by 

the  deposition  of  cork.     These 

(lcn-e-walled  and  nearly  imper 
vious  cells   cohere  together  and 

constitute  a  rind,  which  is  not 

found  in  the  young  and  active 

roots. 

As    to    the    development    of 

the    root-hairs,    they    are    more  Fig.  39. 


Fig.  38. 


THE  VEGETATIVE  ORGANS  OF  PLANTS.        243 

abundant  in  poor  than  in  good  soils,  and  appear  to  be 
most  numerously  produced  from  roots  which  have  other 
wise  a  dense  and  unabsorbent  surface.  The  roots  of  those 
plants  which  are  destitute  of  hairs  are  commonly  of  con 
siderable  thickness  and  remain  white  and  of  delicate  tex* 
ture,  preserving  their  absorbent  power  throughout  the 
whole  time  that  the  plant  feeds  from  the  soil,  as  is  the  case 
with  the  onion. 

The  Silver  Fir,  (Abies  pectinata,}  has  no  root-hairs,  but 
its  rootlets  are  covered  with  a  very  delicate  cuticle  highly 
favorable  to  absorption.  The  want  of  root-hairs  is  further 
compensated  by  the  great  number  of  rootlets  which  are 
formed,  and  which,  perishing  mostly  before  they  become 
superficially  indurated,  are  continually  replaced  by  new 
ones  during  the  growing  season.  (Schacht,  Der  Baum, 
p.  165.) 

Contact  of  Roots  with  the  Soil. — The  root-hairs,  as 
they  extend  into  the  soil,  are  naturally  brought  into  close 
contact  with  its  particles.  This  contact  is  much  more  in 
timate  than  has  been  usually  supposed.  If  we  carefully 
lift  a  young  wheat-plant  from  dry  earth,  we  notice  that 
each  rootlet  is  coated  with  an  envelope  of  soil.  This  ad 
heres  with  considerable  tenacity,  so  that  gentle  shaking 
fails  to  displace  it,  and  if  it  be  mostly  removed  by  vigor 
ous  agitation  or  washing,  the  root-hairs  are  either  found 
to  be  broken,  or  in  many  places  inseparably  attached  to 
the  particles  of  earth. 

Fig.  40  exhibits  the  appearance  of  a  young  wheat- 
plant  as  lifted  from  the  soil  and  pretty  strongly  shaken. 
$,  the  seed ;  #,  the  blade ;  e,  roots  covered  with  hairs  and 
enveloped  in  soil.  Only  the  growing  tips  of  the  roots,  w, 
which  have  not  put  forth  hairs,  come  out  clean  of  soil. 
Fig.  41  represents  the  roots  of  a  wheat-plant  one  month 
older  than  those  of  the  previous  figure.  In  this  instance 
not  only  the  root-tips  are  naked  as  before,  but  the  older 


246 


Fig.  40. 


Fig.  41. 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


247 


parts  of  the  primary  roots,  e,  and  of  the  secondary  roots, 
•>/,  no  longer  retain  the  particles  of  soil ;  the  hairs  upon 
them  being,  in  fact,  dead  and  decomposed.  The  newer 
parts  of  the  root  alone  are  clothed  with  active  hairs,  nnd 
to  these  the  soil  is  firmly  attached  as  before.  The  next  il- 


Fig.  42. 

lustration,  fig.  42,  exhibits  the  appearance  of  root-hairs 
with  adhering  particles  of  earth,  when  magnified  800  di 
ameters — A,  root-hairs  of  wheat-seedling  like  fig.  40;  J?, 
of  oat-plant,  both  from  loamy  soil.  Here  is  plainly  seen 
the  intimate  attachment  of  the  soil  and  root-hairs.  The 


248 


HOW    CHOPS    GROW. 


latter,  in  forcing  their  way  against  considerable  pressure, 
often  expand  around,  and  partially  envelope,  the  particles 
of  earth. 

Imbibition  of  Water  by  the  Root,— The  degree  of 
force  with  which  active  roots  imbibe  the  water  of  the  soil 
is  very  great,  is,  in  fact,  sufficient  to  force  the  liquid  upward 
into  the  stem  and  to  exert  a  con 
tinual  pressure  on  all  parts  of  the 
plant.  When  the  stem  of  a  plant 
in  vigorous  growth  is  cut  off  near 
the  root,  and  a  pressure-gauge  is 
attached  to  it  as  in  fig.  43,  we 
have  the  means  of  observing  and 
measuring  the  force  with  which 
the  roots  absorb  water.  The  pres 
sure-gauge  contains  a  quantity  of 
mercury  in  the  middle  reservoir, 
#,  and  the  tube,  c.  It  is  attached 
to  the  stem  of  the  plant,  p,  by  a 
stout  india-rubber  pipe,  q*  For 
accurate  measurements  the  space, 
a  and  #,  should  be  filled  with  wa 
ter.  Thus  arranged,  it  is  found 
that  water  will  enter  a  through 
the  stem,  and  the  mercury  will 
rise  in  the  tube,  e,  until  its  pres 
sure  becomes  sufficient  to  balance 
the  absorptive  power  of 'the  roots.  Hales,  who  first  ex 
perimented  in  this  manner  140  years  ago,  found  in  one 
instance,  that  the  pressure  exerted  on  a  gauge  attached  in 
spring-time  to  the  stump  of  a  grape  vine,  supported  a 
column  of  mercury  .">:>.]  inches  high,  which  is  equal  to  a 
column  of  water  of  3G£  ft.  Hofrneister  obtained  on  other 
plants,  rooted  in  pots,  the  following  results: 


Fig.  43. 


*  For  expcrimciitin.'  on  small   plants,  a  simple  tube  of  glass  may  be  adjusted 
to  the  eturap  vertically  by  help  of  a  rubber  connector. 


THE    VEGETATIVE    ORGANS    vJF    PLANTS.  249 

Bean  (JPhaseolits  multfflorus)    6  inches  of  mercury. 

Nettle  -      14      " 

Vine      -  29      «  " 

Seat  of  Absorptive  Force,— Dutrochet  demonstrated 
that  this  power  resides  in  the  surface  of  the  young  and 
active  roots.  At  least,  he  found  that  absorption  was  ex 
erted  with  as  much  force  when  the  gauge  was  applied  to 
near  the  lower  extremity  of  a  root,  as  when  attached  in 
the  vicinity  of  the  stem.  In  fact,  when  other  conditions 
are  alike,  the  column  of  liquid  sustained  by  the  roots  of  a 
plant  is  greater,  the  less  the  length  of  stem  that  remains 
attached  to  them.  The  stem  thus  resists  the  rise  of  liquid 
in  the  plant. 

While  the  seat  of  absorptive  power  in  the  root  lies  near 
the  extremities,  it  appears  from  the  experiments  of  Ohlerts 
that  the  extremities  themselves  are  incapable  of  imbibing 
water.  In  trials  with  young  pea,  flax,  lupine,  and  horse 
radish  plants  with  unbranched  roots,  he  found  that  they 
withered  speedily  when  the  tips  of  the  roots  were  immers 
ed  for  about  one-fourth  of  an  inch  in  water,  the  remaining 
parts  being  in  moist  air.  Ohlerts  likewise  proved  that 
these  plants  flourish  when  only  the  middle  part  of  their 
roots  is  immersed  in  water.  Keeping  the  root-tips,  the 
so-called  spongioles,  in  the  air,  or  cutting  them  away  alto 
gether,  was  without  apparent  effect  on  the  freshness  and 
vigor  of  the  plants.  The  absorbing  surface  would  thus 
appear  to  be  confined  to  those  portions  of  the  root  upon 
which  the  development  of  root-hairs  is  noticed. 

The  absorbent  force  is  manifested  by  the  active  rootlets, 
and  most  vigorously  when  these  are  in  the  state  of  most 
rapid  development.  For  this  reason  we  find,  in  case  of  the 
vine,  for  example,  that  during  the  autumn,  when  the  plant 
is  entering  upon  a  period  of  repose  from  growth,  the  ab 
sorbent  power  is  trifling.  The  effect  of  this  forcible  en. 
trance  of  water  into  the  plant  is  oftentimes  to  cause  the 
11* 


250  HOW   CEOPS   GROW. 

exudation  of  it  in  drops  upon  the  foliage.  This  may  be 
noticed  upon  newly  sprouted  maize,  or  other  cereal  plants, 
where  the  water  escapes  from  the  leaves  at  their  extreme 
tips,  especially  when  the  germination  has  proceeded  under 
the  most  favorable  conditions  for  rapid  development. 

The  bleeding  of  the  vine,  when  severed  in  the  spring 
time,  the  abundant  flow  of  sap  from  the  sugar-maple,  and 
the  water-elm,  are  striking  illustrations  of  this  imbibition 
of  water  from  the  soil  by  the  roots.  These  examples  are, 
indeed,  exceptional  in  degree,  but  not  in  kind.  Hofmeister 
has  shown  that  the  bleeding  of  a  severed  stump  is  a  gen 
eral  fact,  and  occurs  with  all  plants  when  the  roots  are 
active,  when  the  soil  can  supply  them  abundantly  with 
water,  and  when  the  tissues  above  the  absorbent  parts  are 
full  of  this  liquid.  When  it  is  otherwise,  water  may  be 
absorbed  from  the  gauge  into  the  stem  and  large  roots,  un 
til  the  conditions  of  activity  are  renewed. 

Of  the  external  circumstances  that  influence  the  absorp 
tive  power  of  the  root,  may  be  noticed  that  of  tempera 
ture.  By  observing  a  gauge  attached  to  the  stump  of 
a  plant  during  a  clear  summer  day,  it  will  be  usually  no 
ticed  that  the  mercury  begins  to  rise  in  the  morning  as 
the  sun  warms  the  soil,  and  continues  to  ascend  for  a  num 
ber  of  hours,  but  falls  again  as  the  sun  declines.  Sachs 
found  in  some  of  his  experiments  that  at  a  temperature  of 
41°  F.,  absorption,  in  case  of  tobacco  and  squash  plants, 
was  nearly  or  entirely  suppressed,  but  was  at  once  renewed 
by  plunging  the  pot  into  warm  water. 

The  external  supplies  of  water, — in  case  a  plant  is  sta 
tioned  in  the  soil,  the  degree  of  moisture  contained  in  this 
medium, — obviously  must  influence,  not  perhaps  the  im 
bibing  force,  but  its  manifestation. 

The  Rate  Of  Absorption  is  subject  to  changes  depend 
ent  on  other  causes  not  well  understood.  Sachs  observed 
that  the  amount  of  liquid  which  issued  from  potato  stalks 


THE    VEGKTATIVE    ORGAXS    OF   PLANTS.  251 

cut  off  just  above  the  ground,  underwent  great  and  con 
tinual  variation  from  hour  to  hour  (during  rainy  weather) 
when  the  soil  was  saturated  with  water  and  when  the 
thermometer  indicated  a  constant  temperature.  Hofmeister 
states  that  the  formation  of  new  roots  and  buds  on  the 
stump  is  accompanied  by  a  sinking  of  the  water  in  the 
pressure-gauge. 

Absorption  of  Nutriment  from  the  Soil,— The  food  of 
the  plant,  so  far  as  it  is  derived  from  the  soil,  enters  it  in 
a  state  of  solution,  and  is  absorbed  with  the  water  which  is 
taken  up  by  the  force  acting  in  the  rootlets.  The  absorp 
tion  of  the  matters  dissolved  in  water  is  in  some  degree 
independent  of  the  absorption  of  the  water  itself,  the  plant 
having,  to  a  certain  extent,  a  selective  power. 

3.  The  Root  as  a  Magazine.  —  In  fleshy  roots,  like 
those  of  the  carrot,  beet,  and  turnip,  the  absorption  of 
nutriment  from  the  soil  takes  place  principally,  if  not  en 
tirely,  by  means  of  the  slender  rootlets  which  proceed 
abundantly  from  all  parts  of  the  main  or  tap-root,  and  es 
pecially  from  its  lower  extremity ;  while  the  fleshy  portion 
serves  as  a  magazine  in  which  large  quantities  of  pectose, 
sugar,  etc.,  are  stored  up  during  the  first  year's  growth 
of  these,  (in  our  latitude,)  biennial  plants,  to  supply  the 
wants  of  the  flowers  and  seed  which  are  developed  the 
second  year.  When  one  of  these  roots  is  put  in  the 
ground  for  a  second  year  and  produces  seed,  it  is  found  to 
be  quite  exhausted  of  the  nutritive  matters  which  it  pre 
viously  contained  in  so  large  quantity. 

In  cultivation,  the  farmer  not  only  greatly  increases  the 
size  of  these  roots  and  the  stores  of  organic  nutritive  ma 
terials  they  contain,  but  by  removing  them  from  the 
ground  in  autumn,  he  employs  to  feed  himself  and  his  cat 
tle  the  substances  that  nature  primarily  designed  to  nour 
ish  the  growth  of  flowers  and  seeds  during  another  sum» 
mer. 


252  HOW   CROPS   GROW. 

Soil-Roots:  Water-Roots:  Air-Roots,— We  may  dis« 
tinguish,  according  to  the  medium  in  which  they  are  formed 
and  grow,  three  kinds  of  roots,  viz. :  soil-roots,  water-roots, 
and  air-roots. 

Most  agricultural  plants,  and  indeed  by  far  the  greater 
number  of  all  plants  found  in  temperate  climates,  have 
roots  adapted  exclusively  to  the  soil,  and  which  perish  by 
drying,  if  long  exposed  to  air,  or  rot,  if  immersed  for  a 
time  in  water. 

Many  aquatic  plants,  on  the  other  hand,  die  if  their 
roots  be  removed  from  water,  or  from  earth  saturated 
with  water. 

Air-roots  are  not  common  except  among  tropical  plants. 
Indian  corn,  however,  often  throws  out  roots  from  the 
lower  joints  of  the  stem,  which  extend  through  the  air 
several  inches  before  they  reach  the  soil.  The  Banyan  of 
India  sends  out  roots  from  its  branches,  which  penetrate 
the  earth  in  like  manner.  Many  tropical  plants,  especially 
of  the  tribe  of  Orchids,  emit  roots  which  hang  free  in  the 
air,  and  never  come  in  contact  with  water  or  soil. 

A  plant,  known  to  botanists  as  the  Zamia  spiralis,  not 
only  throws  out  air-roots,  c  c,  Fig.  44,  from  the  crown  of 
the  main  soil-root,  but  the  side  rootlets,  #,  after  extending 
some  distance  horizontally  in  the  soil,  send  from  the  same 
point,  roots  downward  and  upward,  the  latter  of  which, 
d,  pass  into  and  remain  permanently  in  the  air.  A  is  the 
stem  of  the  plant.  (Schacht,  Anatomie  der  Gewachse,  Bd. 
II,  p.  151.) 

Some  plants  have  roots  which  are  equally  able  to  exist 
and  perform  their  functions,  whether  in  the  soil  or  sub 
merged  in  water.  Many  forms  of  vegetation  found  in 
our  swamps  and  marshes  are  of  this  kind.  Of  agricul 
tural  plants,  rice  is  an  example  in  point.  Rice  will  grow 
in  a  soil  of  ordinary  character,  in  respect  of  moisture,  as 
the  upland  cotton-soils,  or  even  the  pine-barrens  of  the 
Carolinas.  It  flourishes  admirably  in  the  tide  swamps  of 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


253 


the  coast,  where  the  land  is  laid  under  water  for  weeks  at 
a  time  during  its  growth,  and  it  succeeds  equally  well  in 
fields  which  are  flowed  from  the  time  of  planting  to  that 
of  harvesting.  (Russell.  North  America,  its  Agriculture 
and  Climate,  p.  176.)  The  willow  and  alder,  trees  which 
grow  on  the  margins  of  streams,  send  a  part  of  their  roots 
into  soil  that  is  constantly  saturated  with  water,  or  into 


Fig.  44. 

the  water  itself;  while  others  occupy  the  merely  moist  or 
even  dry  earth. 

Plants  that  customarily  confine  their  growth  to  the  soil, 
occasionally  throw  out  roots  as  if  in  search  of  water,  and 
sometimes  choke  up  drain-pipes  or  even  wells,  by  the  pro 
fusion  of  water-roots  which  they  emit. 

At  Welbeck,  England,  a  drain  was  completely  stopped 
by  roots  of  horseradish  plants  at  a  depth  of  7  feet.  At 
Thornsby  Park,  a  drain  16  feet  deep  was  stopped  en 


254  HOW   CROPS   GROW. 

tirely  by  the  roots  of  gorse,  growing  at  a  distance  of  6 
feet  from  the  drain.  (Jour.  Roy.  Ag.  $oc.,  1.  364.) 

In  New  Haven,  Conn.,  certain  wells  are  so  obstructed  by 
the  aquatic  roots  of  the  elm  trees,  as  to  require  cleaning 
out  every  two  or  three  years. 

This  aquatic  tendency  has  been  repeatedly  observed  in 
the  poplar,  cypress,  laurel,  turnip,  mangel-wurzel,  and 
grasses. 

Henrici  surmised  that  the  roots  which  most  cultivated 
plants  send  down  deep  into  the  soil,  even  when  the  latter 
is  by  no  means  porous  or  inviting,  are  designed  especially 
to  bring  up  water  from  the  subsoil  for  the  use  of  the  plant. 
The  following  experiment  was  devised  for  the  purpose  of 
testing  the  truth  of  this  view.  On  the  13th  of  May, 
1862,  a  young  raspberry  plant,  having  but  two  leaves, 
was  transplanted  into  a  large  glass  funnel  filled  with  gar 
den  soil,  the  throat  of  the  funnel  being  closed  with  a  paper 
filter.  The  funnel  was  supported  in  the  mouth  of  a  large 
glass  jar,  and  its  neck  reached  nearly  to  the  bottom  of  the 
latter,  where  it  just  dipped  into  a  quantity  of  water.  The 
soil  in  the  funnel  was  at  first  kept  moderately  moist  by 
occasional  waterings.  The  plant  remained  fresh  and 
slowly  grew,  putting  forth  new  leaves.  After  the  lapse 
of  several  weeks,  four  strong  roots  penetrated  the  filter 
and  extended  down  the  empty  funnel-neck,  through  which 
they  emerged,  on  the  21st  of  June,  and  thenceforward 
spread  rapidly  in  the  water  of  the  jar.  From  this  time 
on,  the  soil  was  not  watered  any  more,  but  care  was  taken 
to  maintain  the  supply  in  the  jar.  The  plant  continued  to 
develope  slowly ;  its  leaves,  however,  did  not  acquire  a 
vivid  green  color,  but  remained  pale  and  yellowish  ;  they 
did  not  wither  until  the  usual  time  late  in  autumn.  The 
roots  continued  to  grow,  and  filled  the  water  more  and 
more.  Near  the  end  of  December  the  plant  had  7-8 
leaves,  and  a  height  of  8  inches  The  water-roots  were 
vigorous,  very  long,  and  beset  with  numerous  fibrils  and 


THE    VEGETATIVE    ORGANS    OF    PLANTS.  2.),) 

buds.  lu  the  funnel  tube  the  roots  made  a  peril  .1  ft  tissue 
of  fibers.  In  the  dry  earth  of  the  funnel  thej  were 
less  extensively  developed,  yet  exhibited  some  juicy  buds. 
The  stem  and  the  young  axillary  leaf-buds  were  also  full 
of  sap.  The  water-roots  being  cut  away,  the  plant  was 
put  into  garden  soil  and  placed  in  a  conservatory,  where 
it  grew  vigorously,  and  in  May  bore  two  offshoots. 

The  experiment  would  indicate  that  plants  may  extend 
a  portion  of  their  roots  into  the  subsoil  chiefly  for  the  pur 
pose  of  gathering  supplies  of  water.  (Henneberg' *s  Jour. 
far  Landwirthschaft,  1863,  p.  280.)  This  growth  towards 
water  must  be  accounted  for  on  the  principles  asserted  in 
the  paragraph — Apparent  Search  for  Food,  (p.  241). 

The  seeds  of  many  ordinary  land  plants — of  plants,  in 
deed,  that  customarily  grow  in  a  dry  soil,  such  as  the  bean, 
squash,  maize,  etc., — will  readily  germinate  in  moist  cot 
ton  or  saw-dust,  and  if,  when  fairly  sprouted,  the  young 
plants  have  their  roots  suspended  in  water,  taking  care 
that  the  seed  and  stem  are  kept  above  the  liquid,  they  will 
continue  to  grow,  and  if  duly  supplied  with  nutriment 
will  run  through  all  the  customary  stages  of  development, 
producing  abundant  foliage,  flowering,  and  perfecting  seeds, 
without  a  moment's  contact  of  their  roots  with  any  soil. 
(See  Water  Culture,  p.  167.) 

li  plants  thus  growing  with  their  roots  in  a  liquid  me 
dium,  after  they  have  formed  several  large  leaves,  be  care 
fully  transplanted  to  the  soil,  they  wilt  and  perish,  unless 
frequently  watered  ;  whereas  similar  plants  started  in  the 
soil,  may  be  transplanted  without  suffering  in  the  slight 
est  degree,  though  the  soil  be  of  the  usual  dryness,  and 
receive  no  water. 

The  water-bred  seedlings,  if  abundantly  watered  as 
often  as  the  foliage  wilts,  recover  themselves  after  a  time, 
and  thenceforward  continue  to  grow  without  the  need  of 
watering. 

It  might  appear  that  the  first-formed  water-roots  are  in- 


256  HOW   CROPS    GROW. 

capable  of  feeding  the  plant  from  a  dry  soil,  and  hence 
the  soil  must  be  at  first  profusely  watered;  after  a  time, 
however,  new  roots  are  thrown  out,  which  are  adapted  to 
the  altered  situation  of  the  plant,  and  then  the  growth 
proceeds  in  the  usual  manner. 

The  reverse  experiment  would  seem  to  confirm  this 
view.  If  a  seedling  that  has  grown  for  a  short  time  only 
in  the  soil,  so  that  its  roots  are  but  twice  .or  thrice  branch 
ed,  have  these  immersed  in  water,  the  roots  already  form 
ed  mostly  or  entirely  perish  in  a  short  time.  They  indeed 
absorb  water,  and  the  plant  is  sustained  by  them,  but  im 
mediately  new  roots  grow  from  the  crown  with  great  ra 
pidity,  and  take  the  place  of  the  original  roots,  which 
become  disorganized  and  useless.  It  is,  however,  only  the 
young  and  active  rootlets,  and  those  covered  with  hairs, 
which  thus  refuse  to  live  in  water.  The  older  parts  of  the 
roots,  which  are  destitute  of  fibrils  and  which  have  nearly 
ceased  to  be  active  in  the  work  of  absorption,  are  not  af 
fected  by  the  change  of  circumstance.  These  facts,  which 
are  due  to  the  researches  of  Dr.  Sachs,  (  Vs.  St.,  2,  p.  13,) 
would  naturally  lead  to  the  conclusion  that  the  absorbent 
surface  of  the  root  undergoes  some  structural  change,  or 
produces  new  roots  with  modified  characters,  in  order  to 
adapt  itself  to  the  medium  in  which  it  is  placed.  It 
would  appear  that  when  this  adaptation  proceeds  rapidly, 
the  plant  is  not  permanently  retarded  in  its  growth  by  a 
irr.-idual  change  in  the  character  of  the  medium  which 
surrounds  its  roots,  as  may  happen  in  case  of  rice  and 
marsh-plants,  when  the  saturated  soil  in  which  they  may 
be  situated  at  one  time,  is  slowly  dried.  Sudden  changes 
of  medium  about  the  roots  of  plants  slow  to  adapt  them 
selves,  would  be  fatal  to  their  existence. 

Nobbe  has,  however,  carefully  compared  the  roots  of 
buckwheat,  as  developed  in  the  soil,  with  those  emitted  in 
w.-iter,  without  being  able  to  observe  any  structural  differ 
The  tact?  detailed  above  admit  of  partial,  if  not 


THE   VEGETATIVE    ORGANS    OF   PLANTS.  2o7 

complete  explanation,  without  recourse  to  the  supposition 
that  soil  and  water-roots  are  essentially  diverse  in  nature. 
When  a  plant  which  is  rooted  in  the  soil  is  taken  up  so 
that  the  fibrils  are  not  broken  or  injured,  and  set  into  wa- 
t<>r,  it  does  not  suffer  any  hindrance  in  growth,  as  Sacha 
has  found  by  late  experiments.  (Experimental  Physi- 
ologie,  p.  177.)  Ordinarily,  the  suspension  of  growth  and 
decay  of  fibrils  and  rootlets  is  due,  doubtless,  to  the 
mechanical  injury  they  suffer  in  removing  from  the  soil. 
Again,  when  a  plant  that  has  been  reared  in  water  is 
planted  in  earth,  similar  injury  occurs  in  packing  the  soil 
about  the  roots,  and  moreover  the  fibrils  cannot  be  brought 
into  that  close  contact  with  the  soil  which  is  necessary  for 
them  to  supply  the  foliage  with  water ;  hence  the  plant 
wilts,  and  may  easily  perish  unless  profusely  watered  or 
shielded  from  evaporation. 

The  issue  of  water  or  soil-roots,  either  or  both,  from 
the  same  plant,  according  to  the  circumstances  in  which  it 
is  placed,  finds  something  analogous  in  reference  to  air- 
roots.  As  before  stated,  these  chiefly  occur  on  tropical 
plants,  or  in  shaded,  warm,  and  very  moist  situations. 
Schacht  informs  us  that  in  the  dark  and  humid  forest  ra 
vines  of  Madeira  and  Teneriffe,  the  Laurus  Canariensis,  a 
large  tree,  sends  out  from  its  stem  during  the  autumn  rains, 
a  profusion  of  fleshy  air-roots,  which  cover  the  trunk  with 
their  interlacing  branches  and  grow  to  an  inch  in  thick 
ness.  The  following  summer,  they  dry  aw.iy  and  fall  to 
the  ground,  to  be  replaced  by  new  ones  in  the  ensuing  au 
tumn.  (Der  jBaum,  p.  172.) 

The  formation  of  air-roots  may  be  very  easily  observed  by  filling  a  t;ill 
vial  with  water  to  the  depth  of  half  an  inch,  inserting  therein  a  branch  of 
a  common  house-plant,  the  Tradescantia  zebrina,  so  that  the  cut  end  of 
the  stem  shall  stand  in  the  water,  and  finally  corking  the  vial  air-tight. 
The  plant,  which  is  very  tenacious  of  life,  and  usually  grows  well  in 
Bpite  of  all  neglect,  is  not  checked  in  its  vegetative  development  by  the 
treatment  just  described,  but  immediately  begins  to  adapt  itself  to  its 
new  circumstances.  In  a  few  days,  if  the  temperature  be  70°  or  there- 
about,  air-roots  will  be  seen  to  issue  from  the  joints  of  the  stem.  These 


2.)8  HOW   CROPS    GROW. 

are  fringed  with  a  profusion  of  delicate  hairs,  and  rapidly  extend  to  a 
length  of  from  one  to  two  inches.  The  lower  ones,  if  they  chance  to 
penetrate  the  water,  become  discolored  and  decay;  the  others,  howevei, 
remain  for  a  long  time  fresh,  and  of  a  white  color. 

As  already  mentioned,  Indian  corn  frequently  produces 
air-roots.  The  same  is  true  of  the  oat,  of  buckwheat,  of 
the  grape-vine,  and  of  other  plants  of  temperate  re 
gions  when  they  are  placed  for  some  time  in  tropical  con 
ditions,  i.  e.,  when  they  grow  in  a  rich  soil  and  their  over 
ground  organs  are  surrounded  by  a  very  warm  and  very 
moist  atmosphere. 

It  has  been  conjectured  that  these  air-roots  serve  to  ab 
sorb  moisture  from  the  air  and  thus  aid  to  maintain  the 
growth  of  the  plant.  This  subject  has  been  studied  by 
linger,  Chatin,  and  Duchartre.  The  observers  first  named 
were  led  to  conclude  that  these  organs  do  absorb  water 
from  the  air.  Duchartre,  however,  denies  their  absorptive 
power.  It  is  probably  true  that  they  can  and  do  absorb 
to  some  extent  the  water  that  exists  as  vapor  in  the  at 
mosphere.  At  the  same  time  they  may  not  usually  con 
dense  enough  to  make  good  the  loss  that  takes  place  in 
other  parts  of  the  plant  by  evaporation.  Hence  the  re 
sults  of  Duchartre,  which  were  obtained  on  the  entire 
plant  and  not  on  the  air-roots  alone.  (Elements  de 
JBotanigue,  p.  216.)  It  certainly  appears  improbable  that 
organs  which  only  develope  themselves  in  a  humid  atmos 
phere,  where  tthe  plant  can  have  no  lack  of  water,  should 
be  specially  charged  with  the  office  of  collecting  moisture 
from  the  air. 

Root-Excretions. — It  has  been  supposed  that  the  roots 
of  plants  perform  a  function  of  excretion,  the  reverse  of 
absorption — that  plants,  like  animals,  reject  matters  which 
are  no  longer  of  use  in  their  organism,  and  that  the  re 
jected  matters  are  poisonous  to  the  kind  of  vegetation 
from  which  they  originated.  De  Candolle,  an  eminent 
French  botanist,  who  first  advanced  this  doctrine,  founded 


THE    VEGETATIVE    ORGANS    OF    PLANTS.  259 

it  upon  the  observation  that  certain  plants  exude  drops 
of  liquid  from  their  roots  when  these  are  placed  in  dry 
sand,  and  that  odors  exhale  from  the  roots  of  other  plants. 
Numerous  experiments  have  been  instituted  at  various 
times  for  the  purpose  of  testing  this  question.  The  most 
extensive  inquiries  we  are  aware  of,  are  those  of  Dr.  Al 
fred  Gyde,  (Trans.  Highland  and  Agr.  Soc.,  1845-7,  p. 
273-92).  This  experimenter  planted  a  variety  of  agricul 
tural  plants,  viz.,  wheat,  barley,  oats,  rye,  beans,  peas, 
vetches,  cabbage,  mustard,  and  turnips,  in  pots  filled  either 
with  garden  soil,  sand,  moss,  or  charcoal,  and  after  they  had 
attained  consideiable  growth,  removed  the  earth,  etc.,  from 
their  roots  by  washing  with  water,  using  care  not  to  in 
jure  or  wound  them,  and  then  immersed  the  roots  in  ves 
sels  of  pure  water.  The  plants  were  allowed  to  remain 
in  these  circumstances,  their  roots  being  kept  in  darkness, 
but  their  foliage  exposed  to  light,  from  three  to  seventeen 
days.  In  most  cases  they  continued  apparently  in  a  good 
state  of  health.  At  the  expiration  of  the  time  of  experi 
ment,  the  water  which  had  been  in  contact  with  the  roots 
was  evaporated,  and  was  found  to  leave  a  very  minute 
amount  of  yellowish  or  brown  matter,  a  portion  of  which 
was  of  organic  and  the  remainder  of  mineral  origin.  Dr. 
Gyde  concluded  from  his  numerous  trials,  that  plants  do 
throw  off  organic  and  inorganic  excretions  similar  in  com 
position  to  their  s.-ip ;  but  that  the  quantity  is  exceedingly 
small,  and  is  not  injurious  to  the  plants  which  furnish 
them. 

In  the  light  of  newer  investigations  touching  the  struc 
ture  of  roots  and  their  adaptation  to  the  medium  which 
happens  to  invest 'them,  we  may  well  doubt  whether  agri 
cultural  plants  in  the  healthy  state  excrete  any  solid  or 
liquid  matters  whatever  from  their  roots.  The  familiar 
excretion  of  gum,  resin,  and  sugar,*  from  the  steins  of 

*  Prom  the  wounded  bark  of  the  Sugar  Pine,  (Pinus  Larnbertiana^  of  Cali 
fornia. 


200  HOW   CROPS    GROW. 

trees  appears  to  result  from  wounds  or  disease,  and  the 
matters  which  in  the  experiments  of  Gyde  and  others 
were  observed  to  be  communicated  by  the  roots  of  plants 
to  pure  water,  probably  came  either  from  the  continual 
pushing  off  of  the  tips  of  the  rootlets  by  Jie  interior 
growing  point — a  process  always  naturally  accompanying 
the  growth  of  roots — or  from  the  disorganization  of  the 
absorbent  root-hairs. 

Under  certain  circumstances,  small  quantities  of  mineral 
salts  may  indeed  diffuse  out  of  the  root-cells  into  the  water 
of  the  soil.  This  is,  however,  no  physiological  action, 
but  a  purely  physical  process. 

Vitality  Of  Roots, — It  appears  that  in  case  of  most 
plants  the  roots  cannot  long  continue  their  vitality  if  their 
connection  with  the  leaves  be  interrupted,  unless,  indeed, 
they  be  kept  at  a  winter  temperature.  Hence  weeds  may 
be  effectually  destroyed  by  cutting  down  their  tops ;  al 
though,  in  many  cases,  the  process  must  be  several  times 
repeated  before  the  result  is  attained. 

The  roots  of  our  root-crops,  properly  so-called,  viz., 
beets,  turnips,  carrots,  and  parsnips,  when  harvested  in  au 
tumn,  contain  the  elements  of  a  second  year's  growth  of 
stem,  etc.,  in  the  form  of  a  bud  at  the  crown  of  the  root. 
It'  the  crown  be  cut  away  from  the  root,  the  latter  cannot 
vegetate,  while  the  growth  of  the  crown  itself  is  not 
thereby  prevented. 

As  regards  internal  structure.,  the  root  closely  resembles 
the  stem,  and  what  is  stated  of  the  latter  on  subsequent 
pages,  applies  in  all  essential  points  to  the  former. 

§2- 

THE    STEM. 

Shortly  after  the  protrusion  of  the  rootlet  from  a  ger 
minating  seed,  the  STEM  makes  its  appearance.  It  has,  in 
general,  an  upward  direction,  which  in  many  plants  is  per- 


THE  VEGETATIVE  ORGANS  OF  PLANTS. 

manent,  while  in  others  it  shortly  falls  to  the  ground  and 
grows  thereafter  horizontally. 

All  plants  of  the  higher  orders  have  stems,  though  in 
many  instances  they  do  not  appear  above  ground,  but  ex 
tend  beneath  the  surface  of  the  soil,  and  are  usually  con 
sidered  to  be  roots. 

While  the  root,  save  in  exceptional  cases,  does  not  de 
velop  other  organs,  it  is  the  special  function  of  the  stem 
to  bear  the  leaves,  flowers,  and  seed,  of  the  plant,  and  even 
in  certain  tribes  of  vegetation,  like  the  cacti,  which  have 
no  leaves,  it  performs  the  offices  of  these  organs.  In  gen 
eral,  the  functions  of  the  stem  are  subordinate  to  those 
of  the  organs  which  it  bears — the  leaves  and  flowers.  It 
is  the  support  of  these  organs,  and  only  extends  in  length 
or  thickness  with  the  apparent  purpose  of  sustaining  them 
either  mechanically  or  nutritively. 

Buds. — In  the  seed  the  stem  exists  in  a  rudimentary 
state,  associated  with  undeveloped  leaves,  forming  a  bud. 
The  stem  always  proceeds  at  first  from  a  bud,  during  all 
its  growth  is  terminated  by  a  bud  at  every  growing  point, 
and  only  ceases  to  be  thus  tipped  when  it  fully  accom 
plishes  its  growth  by  the  production  of  seed,  or  dies  from 
injury  or  disease. 

In  the  leaf -bud 
we  find  a  number 
of  embryo  leaves 
and  leaf-like  scales, 
in  close  contact  and 
within  each  other, 
but  all  attached  at 
the  base,  to  a  cen 
tral  conical  axis, 
fig.  45.  The  open- 
ing  of  the  bud  con 
sists  in  the  lengthening  of  this  axis,  which  is  the  stem, 
and  the  consequent  separation  of  the  leaves  from  each 


262  HOW  CHOPS  GROW. 

other.  If  the  rudimentary  leaves  of  a  bud  W  represented 
by  a  nest  of  flower-pots,  the  smaller  placed  within  the 
larger,  the  stem  may  be  signified  by  a  rope  of  India- 
rubber  passed  through  the  holes  in  the  bottom  of  the 
pots.  The  growth  of  the  stem  may  now  be  shown  by  stretch 
ing  the  rope,whereby  the  pots  are  brought  away  from  each 
other,  and  the  whole  combination  is  made  to  assume  the  char 
acter  of  a  fully  developed  stem,  bearing  its  leaves  at  regular 
intervals ;  with  these  important  differences,  that  the  por 
tions  of  stem  nearest  the  root  extend  more  rapidly  than 
those  above  them,  and  the  stem  has  within  it  the  material 
and  the  mechanism  for  the  continual  formation  of  new 
buds,  which  unfold  in  successive  order. 

In  fig.  45,  which  represents  the  two  terminal  buds  of  a 
lilac  twig,  is  shown  not  only  the  external  appearance  of 
the  buds,  which  are  covered  with  leaf-like  scales,  imbricated 
like  shingles  on  a  roof;  but,  in  the  section,  are  seen  the 
edges  of  the .  undeveloped  leaves  attached  to  the  conical 
axis.  All  the  leaves  and  the  whole  stem  of  a  twig  of  one 
summer's  growth  thus  exist  in  the  bud,  in  plan  and  in 
miniature.  Subsequent  growth  is  but  the  development 
of  the  plan. 

In  the  flower-bud  the  same  structure  is  manifest,  save 
that  the  rudimentary  flowers  and  fruit  are  enclosed  within 
the  leaves,  and  may  often  be  seen  plainly  on  cutting  the 
bud  open. 

Culms;  Nodes;  In  tor  nodes, — The  grasses  and  the  com 
mon  cereal  grains  have  single,  unbranched  steins,  termed 
culms  in  botanical  language.  The  leaves  of  these  plants 
clasp  the  stem  entirely  at  their  base,  and  at  this  point  is 
formed  a  well-defined,  thickened  knot  or  node  in  the  stem 
The  portions  of  the  stem  between  these  nodes  are  termed 
intern*  >des. 

Branching   Stems. — Other  agricultural   plants  besides 
just  mentioned,  ami  all  the  trees  of  temperate  cli- 


THE    VEGETATIVE    ORGANS    OF    PLANTS.  263 

mates,  have  branching  stems,  originating  in  the  following 
manner :  As  the  principal  or  main  stem  elongates,  so  that 
the  leaves  arranged  upon  it  separate  from  each  other, 
we  may  find  one  or  more  side  or  axillary  buds  at  the  point 
where  the  base  of  the  leaf  or  of  the  leaf-stalk  unites  with 
the  stem.  From  these  buds,  in  case  their  growth  is  not 
checked,  side-stems  or  branches  issue,  which  again  sub 
divide  in  the  same  manner  into  branchlets. 

In  perennial  plants,  when  young,  or  in  their  young 
shoots,  it  is  easy  to  trace  the  nodes  and  internodes,  or  the 
points  where  the  leaves  are  attached  and  the  intervening 
spaces,  even  for  some  time  after  the  leaves,  which  only 
endure  for  one  year,  are  fallen  away.  The  nodes  are  mani 
fest  by  the  enlargement  of  the  stem,  or  by  the  scar  covered 
with  corky  matter,  which  marks  the  spot  where  the  leaf 
stalk  was  attached.  As  the  stem  grows  older  these  indi 
cations  of  its  early  development  are  gradually  obliterated. 

In  a  forest  where  the  trees  are  thickly  crowded,  the 
lower  branches  die  away  from  want  of  light ;  the  scars 
resulting  from  their  removal  are  covered  with  a  new 
growth  of  wood,  so  that  the  trunk  finally  appears  as  if  it 
had  always  been  destitute  of  branches,  to  a  great  height. 

When  all  the  buds  develop  normally  and  in  due  propor 
tion,  the  plant,  thus  regularly  built  up,  has  a  symmetrical 
appearance,  as  frequently  happens  with  many  herbs,  and 
also  with  some  of  the  cone-bearing  trees,  especially  the 
balsam-fir. 

Latent  Buds* — Often,  however,  many  of  the  buds  re 
main  undeveloped  either  permanently  or  for  a  time. 
Many  of  the  side-buds  of  most  of  our  forest  and  fruit  treus 
fail  entirely  to  grow,  while  others  make  no  progress  until 
the  summer  succeeding  their  first  appearance.  When  the 
active  buds  are  destroyed,  either  by  frosts  or  by  pinching 
off,  other  buds  that  would  else  remain  latent,  are  pushed 
into  growth.  In  this  way,  trees  whose  young  leaves  are  de 
stroyed  by  spring  frosts,  cover  themselves  again  after  a 


264  now  CHOPS  GBOW. 

time  with  foliage.  In  this  way,  too,  the  gardener  molds  a 
straggling,  ill-shaped  shrub  or  plant  into  almost  any  form 
he  chooses ;  for  by  removing  branches  and  buds  where 
they  have  grown  in  undue  proportion,  he  riot  only  checks 
excess,  but  also  calls  forth  development  in  the  parts  before 
suppressed. 

Adventitious  or  irregular  Buds  are  produced  from  the 
stems  as  well  as  older  roots  of  many  plants,  when  they  are 
mechanically  injured  during  the  growing  season.  The 
soft  or  red  maple  and  the  chestnut,  when  cut  down,  habitu 
ally  throw  out  buds  and  new  stems  from  the  stump,  and 
the  basket-willow  is  annually  polled,  or  pollarded,  to  induce 
the  growth  of  slender  shoots  from  an  old  trunk. 

Elongation  of  Stems. — While  roots  extend  chiefly  at 
their  extremities,  we  find  the  stem  elongates  equally,  or 
nearly  so,  in  all  its  contiguous  parts,  as  is  manifest  from 
what  has  already  been  stated  in  illustration  of  its  devel 
opment  from  the  bud. 

Besides  the  upright  stem,  there  are  a  variety  of  prostrate 
and  in  part  subterranean  stems,  which  may  be  briefly  no 
ticed. 

Runners  and  Layers  are  stems  that  are  sent  out  hori 
zontally  just  above  the  soil,  and  coming  in  contact  with  the 
earth,  take  root,  forming  new  plants,  which  may  thence 
forward  grow  independently.  The  gardener  takes  advan 
tage  of  these  stems  to  propagate  certain  plants.  The 
strawberry  furnishes  the  most  familiar  example  of  runners, 
while  many  of  the  young  shoots  of  the  currant  fall  to  the 
ground  and  become  layers.  The  runner  is  a  somewhat 
peculiar  stem.  It  issues  horizontally,  and  usually  bears 
but  few  or  no  leaves.  The  layer  docs  not  differ  from  an 
ordinary  stem,  except  by  the  circumstance,  often  accident 
al,  of  becoming  prostrate.  Many  plants  which  usually 
scn.l  out  no  layers,  are  nevertheless  artificially  layered  by 
building  their  steins  or  branches  to  the  ground,  or  by  at- 


THE    VEGETATIVE    ORGANS    OF   PLANTS.  265 

taching  to  them  a  ball  or  pot  of  earth.  The  striking  out 
of  roots  from  the  layer  is  in  many  cases  facilitated  by  cut 
ting  half  off,  twisting,  or  otherwise  wounding  the  stem  at 
the  point  where  it  is  buried  in  the  soil. 

The  tillering  of  wheat  and  other  cereals,  and  of  many 
grasses,  is  the  spreading  of  the  plant  by  layers.  The  first 
stems  that  appear  from  these  plants  ascend  vertically,  but, 
subsequently,  other  stems  issue,  whose  growth  is,  for  a 
time,  nearly  .horizontal.  They  thus  come  in  contact  with 
the  soil,  and  emit  roots  from  their  lower  joints.  From 
these  again  grow  new  stems  and  new  roots  in  rapid  suc 
cession,  so  that  a  stool  produced  from  a  single  kernel  of 
winter  wheat,  having  perfect  freedom  of  growth,  has  been 
known  to  carry  50  or  60  grain-bearing  culms.  (Hallet, 
Jour.  Roy.  Soc.  of  Eng.,  22,  p.  372.) 

Subterranean  Stems, — Of  these  there  are  three  forma 
agriculturally  interesting.  They  are  usually  thought  to  be 
roots,  from  the  fact  of  existing  below  the  surface  of  the 
soil.  This  circumstance  is,  however,  quite  accidental. 
The  pods  of  the  pea-nut  ripen  beneath  the  ground — the 
flower-stems  lengthening  and  penetrating  the  earth  as 
soon  as  the  blossom  falls  ;  but  pea-nuts  are  not  by  any 
means  to  be  confounded  with  roots. 

Root-Stocks. — As  before  remarked,  true  roots  are  desti 
tute  of  buds,  and, 'we  may  add,  of  leaves.  This  fact  dis 
tinguishes  them  from  the  so-cnlled  creeping-root,  which  is 
a  stem  that  extends  just  below  the  surface  of  the  soil, 
emitting  roots  throughout  its  entire  length.  At  intervals 
along  these  root-stocks,  as  they  are  appropriately  named, 
scales  are  formed,  which  represent  rudimentary  leaves, 
In  the  axils  of  the  scales  may  be  traced  the  buds  from 
which  aerial  stems  proceed.  Examples  of  the  root-stock 
are  very  common.  Among  them  we  may  mention  the 
blood-root  and  pepper-root  as  abundant  in  the  woods  of 
the  Northern  and  Middle  States,  and  the  quack-grass, 
12 


265  HOW    CROPS    GIJOW, 

represented  in  fig.  46,  which  infests  so  many  farms.  Each 
node  of  the  root-stock,  being  usually  supplied  with  roots, 
and  having  latent  buds,  is  ready  to  become  an  independ 
ent  growth  the  moment  it  is  detached  from  its  parent 
plant.  In  this  way  quack-grass  becomes  especially  troub 


lesome  to  the  farmer,  for,  within  certain  limits,  the  more 
he  harrows  the  fields  where  it  has  obtained  a  footing,  the 
more  does  it  spread  and  multiply. 

Slickers, — The  rose,  raspberry,  and  cherry,  are  examples 
of  plants  which  send  out  subterranean  branches,  analogous 
to  tho  root-stock.  These  coining  to  the  surface,  become 
aerial  stems,  and  are  then  termed  snckerx. 

The  Tubers  of  most  agricultural  plants  are  fleshy  en 
largements  of  the  extremities  of  subterranean  stems. 
Their  eyes  are  the  points  where  the  buds  exist,  usually 
three  together,  and  where  minute  scales  —  rudimentary 
leaves— may  be  observed.  The  common  potato  and  arti 
choke  are  instances  of  tubers.  Tubers  serve  excellently 
r=r  propagation.  Kadi  eye,  or  Imd,  may  become  a  new 
plant.  From  the  quantity  of  starch,  etc.,  accumulated  in 
lhe:n,  they  arc  of  great  importance  as  food.  The  number 
of  tubers  produced  by  a  potato-plant  appears  to  be  in 
creased  by  planting  originally  at  a  considerable  depth,  or 
by  "hilling  up"  earth  around  the  Lase  of  the  aerial  stemV, 
during  tl«"  early  stages  of  its  growth. 


THE   VEGETATIVE   ORGANS    OF   PLANTS.  26? 

Bulbs  are  the  lower  parts  of  stems,  greatly  thickened, 
the  mternod.es  being  undeveloped,  while  the  leaves — usu 
ally  scales  or  concentric  coats — are  in  close  contact  with 
each  other.  The  bulb  is,  in  fact,  a  fleshy,  permanent  bud, 
usually  in  part  or  entirely  subterranean.  From  its  apex, 
the  proper  stem,  the  foliage,  etc.,  proceed;  while  from 
its  base,  roots  are  sent  out.  The  structural  identity 
of  the  bulb  with  a  bud  is  sho\vn  by  the  fact  that  the  onion 
which  furnishes  the  commonest  example  of  the  bulb,  often 
bears  bulblets  at  the  top  of  its  stem,  in  place  of  flowers. 
In  like  manner,  the  axillary  buds  of  the  tiger-lily  are 
thickened  and  fleshy,  and  fall  off  as  bulblets  to  the  ground, 
where  they  produce  new  plants. 

STRUCTURE  OF  THE  STEM. — The  stem  is  so  complicated 
in  its  structural  composition  that  to  discuss  it  fully  would 
occupy  a  volume.  For  our  immediate  purposes  it  is, 
however,  only  necessary  to  notice  it  very  concisely. 

The  rudimentary  stem,  as  found  in  the  seed,  or  the  new- 
formed,  part  of  fche  maturer  stem  at  the  growing  points 
just  below-  the  terminal  buds,  consists  of  cellular  tissue, 
i.  e.,  of  an  aggregate  of  rounded  and  cohering  cells,  which 
rapidly  multiply  during  the  vigorous  growth  of  the  plant. 

In  some  of  the  lower  orders  of  vegetation,  as  in  mush 
rooms  and  lichens,  the  stem,  if  any  exist,  always  preserves 
a  purely  cellular  character;  but  in  all  flowering  plants  the 
original  cellular  tissue  of  the  stem,  as  well  as  of  the  root, 
is  shortly  penetrated  by  vascular  tissue,  consisting  of  ducts 
or  tubes,  which  result  from  the  obliteration  of  the  hori 
zontal  partitions  of  cell-tissue,  and  by  wood-cells,  which  are 
many  times  longer  than  wide,  and  the  walls  of  which  are 
much  thickened  by  internal  deposition. 

These  ducts  and  wood-cells,  together  with  some  other 
forms  of  cells,  are  usually  found  in  close  connection,  and 
are  arranged  in  bundles,  which  constitute  the  fibers  of  the 
stem.  They  are  always  disposed  lengthwise  in  the  stem 
and  branches.  They  are  found  to  some  extent  in  the  soft- 


268  HOW    CHOPS    GROW. 

est  herbaceous  stems,  while  they  constitute  a  large  share 
of  the  trunks  of  most  shrubs  and  trees.  From  the  tough 
ness  which  they  possess,  and  the  manner  in  which  they 
are  woven  through  the  original  cellular  tissue,  they  give 
to  the  stem  its  solidity  and  strength. 

The  flowering  plants  of  temperate  climates  may  be  di 
vided  into  two  great  classes,  in  consequence  rf  important 
and  obvious  differences  in  the  structure  of  their  stems  and 
seeds.  These  are,  1,  Endogenous  or  Monocotyledonous  • 
and,  2,  Exogenous  or  Dicotyledonous  plants.  As  regards 
their  stems,  these  two  classes  of  plants  differ  in  the  ar 
rangement  of  the  vascular  or  wroody  tissue. 

Endogenous  Plants  are  those  whose  stems  enlarge  by 
the  formation  of  new  wood  in  the  interior,  and  not  by  the 
external  growth  of  concentric  layers.  The  seeds  of  endog 
enous  plants  consist  of  a  single  piece — do  not  readily 
split  into  halves, — or,  in  botanical  language,  have  but  one 
cotyledon;  hence  are  called  monocotyledonous.  Indian 
corn,  sugar  cane,  sorghum,  wheat,  oats,  rye,  barley,  the 
onion,  asparagus,  and  all  the  grasses,  belong  to  this  tribe 
of  plants. 

If  a  stalk  of  maize,  asparagus,  or  bamboo,  be  cut  across, 
the  bundles  of  ducts  are  seen  disposed  somewhat  uni- 


formly  throughout  the  section,  though  less  abundantly  to 
wards  the  center.  On  splitting  the  fresh  stalk  lengthwise, 
the  vascular  bundles  may  be  torn  out  like  strings.  At 
the  nodes,  where  the  stem  branches,  or  where  leaf-stalks 
are  attached,  the  vascular  bundles  likewisj  divide  and 
form  a  not-work,  or  plexus.  In  a  ripe  maize-stalk  which  is 
exposed  to  circumstances  favoring  decay,  the  soft  cell-tis 
sue  first  suffers  change  an  1  often  quite  disappears,  leaving 


THE   V^GETAnVE    ORGANS    OF   PLANTS.  269 

the  firmer  vascular  bundles  unaltered  in  form.  A  portion 
of.  the  base  of  such  a  stalk,  cut  lengthwise,  is  represented 
in  figure  47,  where  are  seen  the  duct-fibers  arranged  par 
allel  to  each  other  in  the  internodes,  and  curiously  inter 
woven  and  branched  at  the  nodes,  either  those,  a  and  #, 
from  which  roots  issue,  or  that,  c,  which  was  clasped  by 
the  base  of  a  leaf. 

The  endogenous  stem,  as  represented  in  the  maize-stalk, 
has  no  well-defined  bark  that  admits  of  being  stripped  off 
externally,  and  no  separate  central  pith  of  soft  cell-tissue 
free  from  vascular  bundles.  It,  like  the  aerial  portions  of 
all  flowering  plants,  is  covered  with  a  skin,  or  epidermis, 
composed  usually  of  one  or  several  layers  of  flattened 
cells,  whose  walls  are  thick,  and  far  less  penetrable  to 
fluid  than  the  delicate  texture  of  the  interior  cell-tissue. 
The  stem  is  denser  and  harder  at  the  circumference  than 
towards  the  center.  This  is  due  to  the  fact  that  the  fibers 
are  more  numerous  and  older  towards  the  outside  of  the 
stem.  The  newer  fibers,  as  they  continually  form,  grow 
in  the  inside  of  the  stem,  and  hence  the  designation  endog 
enous,  which  in  plain  English  means  inside-grower. 

In  consequence  of  this  inner  growth,  the  stems  of  most 
woody  endogens,  as  the  palms,  after  a  time  become  so  in 
durated  externally,  that  all  lateral  expansion  ceases,  and 
the  stem  increases  only  in  height.  It  grows,  nevertheless, 
internally,  new  fibers  developing  in  the  softer  portions, 
until,  in  some  cases,  the  tree  dies  because  its  interior  is  so 
closely  packed  with  fibers  that  the  formation  of  new  ones, 
and  the  accompanying  vital  processes,  become  impossible. 

In  herbaceous  endogens  the  soft  stem  admits  the  indefi 
nite  growth  of  new  vascular  tissue. 

The  stems  of  the  grasses  are  hollow,  except  at  the 
nodes.  Those  of  the  rushes  have  a  central  pith  free  from 
vascular  tissue. 

F  The  Minute  Structure  of  the  Endogenous  Stem  is  ex 
hibited  in  the  accompanying  cuts,  which  represent  highly 


270 


HOW   CROPS    GROW. 


magnified  sections  of  a  VascMlar  Bundle  or  fiber  from  the 
mnize-stalk.  As  before  remarked,  the  stem  is  composed 
of  a  ground- work  of  delicate  cell-tissue,  in  which  bundles 
of  vascular  tissue  are  distributed.  Fig.  48  represents  a 
cross  section  of  one  of  these  bundles,  c,  ^,  A,  as  well  as 


of  a  portion  of  the  surrounding  coil-tissue,  a,  a.  The 
latter  consists  of  quite  large  cells,  which,  being  but  loosely 
packed  together,  have  between  them  considerable  inter 
cellular  spaces,  /.  The  vascular  bundle  itself  is  composed 
externally  of  narrow,  thick-walled  cells,  of  which  those 
nearest  the  exterior  of  the  stem,  A,  are  termed  bast-cells, 
as  they  correspond  in  character  and  position  to  the  cells 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


271 


of  the  bast  or  inner  bark  of  our  common  trees;  those 
nearest  the  centre  of  the  stem,  c,  are  icood-cells.  In  the 
maize  stem,  bast  and  wood-cells  are  quite  alike,  and 
are  distinguished  only  by  their  position.  In  other  plants, 
they  are  often  unlike  as  regards  length,  thickness,  and  pli 
ability,  though  still,  for  the  most  part,  similar  in  form. 
Among  the  wood-cells  we  observe  a  number  of  ducts,  d, 
e,f,  and  between  these  and  the  bast-cells  is  a  delicate  and 
transparent  tissue,  g,  which  is  the  cawbium — in  which  all 
the  growth  of  the  bundle  goes  on  until  it  is  complete.  On 


H 


nun 


i 


Fig.  49. 


either  hand  is  seen  a  remarkably  large  duct,  #,  #,  while  the 
residue  of  the  bundle  is  composed  of  long  and  rather 
thick-walled  wood-cells. 

Our  understanding  of  these  parts  will  be  greatly  aided 
by  a  study  of  fig.  49,  which  represents  a  section  made 
vertically  through  the  bundle  from  c  to  h,  cutting  the  va 
rious  tissues  and  revealino-  more  of  their  structure.  In  this 

O 

the  letters  refer  to  the  same  parts  as  in  the  former  cut : 
«,  #,  is  the  cell-tissue,  enveloping  the  vascular  bundle; 
the  cells  are  observed  to  be  much  longer  than  wide,  but 
are  separated  from  each  other  at  the  ends  as  well  as  sides 


272  HOW   CROPS   GROW. 

by  an  imperforate  membrane.  The  wood  and  baat-cells,  c, 
hj  are  seen  to  be  long,  narrow,  thick-walled  cells  running 
obliquely  to  a  point  at  either  end.  The  wood-cells  of  oak, 
hickory,  and  the  toughest  woods,  as  well  as  the  bast-cells 
of  flax  and  hemp,  are  quite  similar  in  form  and  appearance. 
The  proper  ducts  of  the  stein  are  next  in  the  order  of  our 
section.  Of  these  there  are  several  varieties,  as  ring-ducts, 
d;  spiral  ducts,  e  ;  dotted  ducts,  f.  These  are  continuous 
tubes  produced  by  the  resorption  of  the  transverse  mem 
branes  that  once  divided  them  into  such  cells  as  a,  a,  and 
they  are  thickened  internally  by  ring-like,  spiral,  or  punc 
tate  depositions  of  cellulose,  (see  fig.  32,  p.  227.)  Wood- 
cells  that  consist  exclusively  of  cellulose  are  pliant  and 
elastic.  It  is  the  deposition  of  lignin  in  their  walls  which 
renders  them  stiff  and  brittle. 

At  g.  the  cambium  tissue  is  observed  to  consist  of  deli 
cate  cylindrical  cells.  Among  these,  partial  resorption  of 
the  separating  membrane  often  occurs,  so  that  they  com 
municate  directly  with  each  other  through  sieve-like  parti 
tions,  and  become  continuous  channels  or  ducts,  (sieve-cells, 
[..  280.) 

The  cambium  is  the  seat  of  growth  by  cell-formation. 
Accordingly,  when  a  vascular  bundle  has  attained  maturi 
ty,  it  no  longer  possesses  a  cambium ;  the  latter  has  grown 
away  from  it,  has  reproduced  itself  in  originating  a  new 
vascular  bundle,  which,  in  case  of  the  endogens,  branches 
off  from  the  present  bundle,  and  with  exogens,  runs  paral 
lel  with,  and  exterior  to  the  latte'r. 

To  complete  our  view  of  the  vascular  bundle,  fig.  50 
represents  a  vertical  section  made  at  right  angles  to  the 
last,  cutting  two  large  ducts,  b,  b  ;  a,  a,  is  cell-tissue;  c 
c,  are  bast  or  wood-cells  less  thickened  by  interior  deposi 
t:on  than  those  of  fig.  49;  d,  is  a  ring  and  spiral  duct;  6, 
£>,  are  large  dotted  ducts,  which  exhibit  at  g,  g,  the  places 
where  they  were  once  crossed  by  the  double  membrane 
composing  the  ends  of  two  adhering  cells,  by  whose  al> 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


273 


sorption  and  removal  an  uninterrupted  tube  has  been 
formed.  In  these  large  dotted  ducts  there  appears  to  be 
no  direct  communication  with  the  surrounding  cells 
through  their  sides.  The  dots  or  pits  are  simply  very  thin 
points  in  the  cell-wall,  through  which  sap  may  soak  ot 
diffuse  laterally,  but  not  flow'.  When  the  cells  become 
mature  and  cease  growth,  the  pits  often  become  pores  by 


M 
ri 


, 


M 
'"I 


Fig.  50. 


absorption  of  the  membrane,  so  that  the  ducts  thus  enter 
into  direct  communication  with  each  other. 

Exogenous  plants  are  those  whose  stems  continually 
enlarge  in  diameter  by  the  formation  of  new  tissue  near 
the  outside  of  the  stem.  They  are  outs ide-g rowers.  Their 
seeds  are  usually  made  up  of  two  loosely  united  parts,  or 
cotyledons,  wherefore  they  are  designated  dicotyledonous. 
All  the  forest  trees  of  temperate  climates,  and,  among 
agricultural  plants,  the  bean,  pea,  clover,  potato,  beet,  tur 
nip,  flax,  etc.,  are  exogens. 

In  the  exogenous  stem  the  bundles  of  ducts  and  fibers 
that  appear  in  the  cell-tissue  are  always  formed  just  within 
12* 


274  HOW   CROPS   GROW. 

the  epidermis.  They  occur  at  first  separately,  as  in  the 
endogens,  but  instead  of  being  scattered  throughout  the 
cell- tissue,  are  disposed  in  a  circle.  As  they  grow,  they 
usually  close  up  to  a  ring  or  zone  of  wood,  which,  within, 
incloses  unaltered  cell-tissue — the  pith — and  without,  in 
Bhrubs  and  trees,  is  covered  by  rind. 

As  the  stem  enlarges,  new  rings  of  fibers  may  be  form 
ed,  but  always  outside  of  the  older  ones.  In  hard  stems 
of  slow  growth  the  rings  are  close  together  and  chiefly 
consist  of  very  firm  wood-cells.  In  the  soft  stems  of  herbs 
the  cell-tissue  preponderates,  and  the  ducts  and  cells  of 
the  vascular  zones  are  delicate.  The  hardening  of  herba 
ceous  stems  which  takes  place  as  they  become  mature,  is 
due  to  the  increase  and  induration  of  the  wood-cells 
and  ducts. 

The  circular  disposition  of  the  fibers  in  the  exogenous 
stem  may  be  readily  seen  in  a  multitude  of  common 
plants. 

The  potato  tuber  is  a  form  of  stem  always  accessible 
for  observation.  If  a  potato  be  cut  across  near  the  stem- 
end  with  a  sharp  knife,  it  is  usually  easy  to  identify  upon 
the  section  a  ring  of  vascular  tissue,  the  general  course  of 
which  is  parallel  to  the  circumference  of  the  tuber  except 
where  it  runs  out  to  the  surface  in  the  eyes  or  buds,  and 
in  the  narrow  stem  at  whose  extremity  it  grows.  If  a 
slice  across  a  potato  be  soaked  in  solution  of  iodine  for  a 
few  minutes,  the  vascular  rings  become  strikingly  apparent. 
In  its  active  cambial  cells,  albuminoids  are  abundant,  which 
assume  a  yellow  tinge  with  iodine.  The  starch  of  the  cell- 
tissue,  on  the  other  hand,  becomes  intensely  blue,  making 
the  vascular  tissue  all  the  more  evident. 

Since  the  structure  of  the  root  is  quite  similar  to  that 
of  the  stem,  a  section  of  the  common  beet  as  well  as  one 
of  a  branch  from  any  tree  of  temperate  latitudes  may 
serve  to  illustrate  the  concentric  arrangement  of  the 
vascular  zones  when  they  are  multiplied  in  number. 


THE    VEGETATIVE    ORGANS    OF    j-i«t_i».i.«*r   > 

<  ; 

./•^A  is  the  cell-tissue  of  the  center  ofVthe  stem.  In 
young  stems  it  is  charged  with  juices ;  in  olde&ones  it  often 
becomes  dead  and  sapless.  In  many  cases,  especially  when 
growth  is  active,  it  becomes  broken  and  nearly  obliterated, 
leaving  a  hollow  stem,  as  in  a  rank  pea-vine,  or  c^^i^ 
stalk,  or  in  a  hollow  potato.  In  the  potato  tuber  the  pith- 
cells  are  occupied  throughout  with  starch,  although,  as  the 
coloration  by  iodine  makes  evident,  the  quantity  of  starch 
diminishes  from  the  vascular  zone  towards  the  center  of 
the  tuber. 

The  Rind,  which,  at  first,  consists  of  mere  epidermis, 
or  short,  thick- walled  cells,  overlying  soft  cellular  tissue, 
becomes  penetrated  with  cells  of  unusual  length  and  te 
nacity,  which,  from  their  position  in  the  plant,  are  often 
termed  bast-cells.  These,  together  with  ducts  of  various 
kinds,  all  united  firmly  by  their  sides,  constitute  the  so- 
called  bast-fibers,  which  grow  chiefly  upon  the  interior  of 
the  rind,  in  close  proximity  to  the  wood.  With  their 
abundant  development  and  with  age,  the  rind  becomes 
bark  as  it  occurs  on  shrubs  and  trees.  The  bast-cells  give 
to  the  bark  its  peculiar  toughness,  and  cause  it  to  come 
off  the  stem  in  long  and  pliant  strips. 

Bast-mats  are  made  by  weaving  together  strips  of  the 
inner  bark  of  the  Linden  (bass  or  bast-wood)  tree ;  and  all 
the  textile  materials  employed  in  making  cloth  and  cord 
age,  with  the  exception  of  cotton,  as  flax, hemp,  New  Zea 
land  flax,  etc.,  are  bast-fibers.  The  leather-wood  or  moose- 
wood  bark  often  employed  for  tying  flour-bags,  has  bast- 
fibers  of  extraordinary  tenacity. 

The  external  rind,  like  the  interior  pith,  becomes  sapless 
and  dead  in  perennial  plants,  and  after  a  longer  or  shorter 
period  falls  away.  The  outer  bark  of  the  grape  separates 
in  long  shreds  a  year  or  two  after  its  formation.  On  most 
forest  trees  the  bark  remains  for  several  or  many  years. 
The  expansion  of  the  tree  furrows  the  bark  with  numeroug 


276 


HOW   CROPS   GJ1OW. 


tn 


* 


and  deep  longitudinal   rifts,  and   it  gradually  decays  or 
drops  away  exteriorly  as  the  newer  bark  forms  within. 

Cork  is  one  form  which  the  epidermal  cells  assume  on 
the  stem  of  the  cork  oak,  on  the  potato  tuber,  and  many 
other  plants. 

^  Pith  Rays.  —  Those  portions  of  the  first-formed  cell- 
tissue  which  were  interposed  between  the  young  and  orig 
inally  ununited  wood-fibers  remain,  and  connect  the  pith 
with  the  rind.  In  hard  stems 
they  become  flattened  by  the 
pressure  of  the  fibers,  and  are 
readily  seen  in  most  kinds  of  wood 
when  split  lengthwise.  They  are 
especially  conspicuous  in  the  oak 
and  maple,  and  form  what  is  com 
monly  known  as  the  silver-grain. 
The  botanist  terms  them  pith-rays 
or  medullary  rays. 

Fig.  51  exhibits  a  section  of  a 
bit  of  wood  of  the  Red  Pine, 
(Finns  picea,)  magnified  200  di 
ameters.  The  section  is  made 
tangential  to  the  stem  and  length 
wise  of  the  wood-cells,  four  of 
whicli  are  in  part  represented,  A  / 
it  cuts  across  the  pith-rays,  whose 
werr-structure  and  position  in  the  wood  are  seen  at  m,  n. 

('<nnl>ium  of  Exogens. — The  growing  part  of  the  exog- 
,/ious  stem  is  thus  found  between  the  wood  and  the  bark, 
or  rather  between  the  fully  formed  wood  and  the  mature 
bark.  There  is,  in  fact,  no  definite  limit  where  wood  ceases 
and  bark  begins,  for  they  are  connected  by  the  cambial  or 
formative  tissue,  from  which,  on  the  one  hand,  wood-fibers, 
and  on  the  other,  bast-fibers,  or  the  tissues  of  the  bark, 
rapidly  develope.  In  the  cambium,  likewise,  the  pith-rays 


Fig.  51. 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


277 


which  connect  the  inner  arid  outer  parts  of  the  stem,  con 
tinue  their  outward  growth. 

In  spring-time  the  new  cells  that  form  in  the  cambial 
region  are  very  delicate  and  easily  broken.  For  this  rea 
son  the  rind  or  bark  may  be  stripped  from  the  wood  with 
out  difficulty.  In  autumn  these  cells  become  thickened 
and  indurated,  become,  in  fact,  full-grown  bast  and  wood- 
cells,  so  that  to  peel  the  bark  off  smoothly  is  impossible. 

Minute  Structure  of  Exogenous  Stems, — The  accom 
panying  figure  (52)  will  serve  to  convey  an  idea  of  the  mi 
nute  structure  of  the  elements  of  the  exogenous  stem.  It 


exhibits  a  highly  magnified  section  lengthwise,  through  a 
young  potato  tuber.  A,  by  is  the  rind ;  e,  is  the  vascular 
ring ;  /*,  the  pith.  The  outer  cells  of  the  rind  are  convert 
ed  into  cork.  They  have  become  empty  of  sap  and  are 
nearly  impervious  to  air  and  moisture.  This  corky-layer, 
a*  constitutes  the  thin  coat  or  skin  that  may  be  so  readily 
peeled  off  from  a  boiled  potato.  Whenever  a  potato  is 
superficially  wounded,  even  in  winter  time,  the  exposed 
part  heals  over  by  the  formation  of  cork-cells.  The  cell- 
tissue  of  the  rind  consists  at  its  center,  £,  of  full-formed 
cells  with  delicate  membranes  which  contain  numerous 
and  large  starch  grains.  On  either  hand,  as  the  rind  ap- 


*  The  bracket,  a,  is  much  too  long,  and  b  ie  correspondingly  too  short  in  the 


cut 


278 


HOW    CROPS    GROW. 


preaches  the  corky-layer  or  the  vascular  ring,  the  cells  are 
smaller,  and  contain  smaller  starch  grains;  either  side  of 
these  are  noticed  cells  containing  no  starch,  but  having 
nuclei,  c,  y.  These  nucleated  cells  are  capable  of  multi 
plication,  and  they  are  situated  where  the  growth  of  the 
tuber  takes  place.  The  rind,  which 
makes  a  large  part  of  the  flesh  of  the 
potato,  increases  in  thickness  by  the 
formation  of  new  cells  within  and  with 
out.  Without,  where  it  joins  the  corky 
skin,  the  latter  likewise  grows.  Within, 
contiguous  to  the  vascular  zone,  new 
ducts  are  formed.  In  a  similar  manner, 
the  pith  expands  by  formation  of  new 
cells,  where  it  joins  the  vascular  tissue. 
The  latter  consists,  in  our  figure,  of  ring, 
spiral,  and  dotted  ducts,  like  those  al 
ready  described  as  occurring  in  the 
maize-stalk.  The  delicate  cambial  cells, 
r,  are  in  the  region  of  moct  active 
growth.  At  this  point  new  cells  rap 
idly  develope,  those  to  the  right,  in  the 
figure,  remaining  plain  cells  and  becom 
ing  loosely  filled  with  starch ;  those  to 
the  left  developing  new  ducts. 

In    the    slender,  overground   potato- 
stem,  as  in  all  the  stems  of  most  agricul- 
tural  plants,  the  same  relation  of  parts 
is  to  be  observed,  although  the  vascular 
and  woody  tissues  often  preponderate. 
Wood-cells   arc  especially   abundant  in 
those  stems  that  need  strength  for  the  fulfilment  of  their 
offices,  and  in  them,  especially  in  those  of  our  trees,  the 
structure  is  commonly  more  complicated. 

Perforation  of  Wood-Cells  in  the  Conifers.— In  the 

wood  of  cone-bearing  trees  there  are  no  proper  ducts,  such 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


279 


as  have  been  described.  To  answer  the  purpose  of  air 
and  sap-channels,  the  wood-cells  which  constitute  the  con 
centric  rings  of  the  old  wood  are  constructed  in  a  special 
manner,  being  provided  laterally  with  visible  pores,  through 
which  the  contents  of  one  cell  may  pass  directly  into  those 
of  its  neighbors.  Fig 
53,  B,  represents  a  por 
tion  of  an  isolated  wood- 
cell  of  the  Scotch  Fir, 
(Pinus  sylvestris,}  mag 
nified  200  diameters. 
Upon  it  are  seen  nearly 
circular  clicks,  a?,  y,  the 
structure  of  which,  while 
the  cell  is  young,  is 
shown  by  a  section 
through  them  length 
wise.  A  exhibits  such 
a  section  through  the 
thickened  walls  of  two 
contiguous  and  adhering 
cells,  x,  in  both  A  and 
J3,  shows  a  cavity  be 
tween  the  two  primary 
cell-walls ;  y  is  the  nar 
row  part  of  the  chan 
nel,  that  remains  while 
the  membrane  thickens 
around  it.  This  is  seen 
in  .Z?,  y,  as  a  pore  or 
opening  in  the  cell.  In 
A  it  appears  closed  because  the  section  passes  a  little  to 
one  side  of  the  pore. 

In  the  next  figure,  (54,)  representing  a  transverse  sec 
tion  of  the  spring  wood  of  the  same  tree  magnified  300 
diameters,  the  structure  and  the  gradual  formation  of 


280  HOW   CROPS   GROW. 

these  pore  disks  is  made  evident.  The  section,  likewise, 
gives  an  instructive  illustration  of  the  general  character 
of  the  simplest  kind  of  wood.  JR,  are  the  young  cells  of 
the  rind ;  C,  is  the  cambium,  where  cell  multiplication 
goes  on ;  W,  is  the  wood,  whose  cells  are  more  developed 
the  older  they  are,  i.  e.,  the  more  distant  from  the  cam 
bium,  as  is  seen  from  their  figure  and  the  thickness  of 
their  walls.  At  a  is  shown  the  disk  in  its  earliest  stage ;  £ 
and  c  exhibit  it  in  a  more  advanced  growth  before  it  be 
comes  a  pore,  the  original  cell-wall  being  still  in  place, 
At  d,  in  the  finished  wood-cells,  the  disk  has  become  a 
pore,  the  primary  membrane  has  been  absorbed,  and  a  free 
channel  made  between  the  two  cells.  The  dotted  lines  at 
d  lead  out  laterally  to  two  concentric  circles,  which  repre 
sent  the  disk-pore  seen  flatwise,  as  in  fig.  53.  At  0,  the 
section  passes  through  the  new  annual  ring  into  the  au 
tumn  wood  of  the  preceding  year. 

Sieve-cells  or  sieve-ducts, — The  spiral,  ring,  and  dotted 
ducts  and  porous  wood-cells  already  noticed,  appear  only 
in  the  older  parts  of  the  vascular  bundles,  and  although 
they  are  occupied  with  sap  at  times  wheii  the  stem  is  sur 
charged  with  water,  they  are  ordinarily  filled  with  air 
alone.  The  real  transmission  of  the  nutritive  juices  of  the 
growing  plant,  so  far  as  it  goes  on  through  actual  tubes,  is 
now  admitted  to  proceed  in  an  independent  set  of  ducts, 
the  so-called  sieve-cells,  which  are  usually  near  to,  and 
originate  from  the  cambium.  These  are  extremely  deli 
cate,  elongated  cells,  whose  transverse  or  lateral  walls  are 
perforated,  sieve-fashion,  (by  absorption  of  the  original 
membrane,)  so  as  to  establish  direct  communication  from 
one  to  another,  and  this  occurs  while  they  are  yet  charged 
with  juices  and  at  a  time  when  the  other  ducts  are  occu 
pied  with  air  alone.  These  sieve-ducts  are  believed  to  be 
the  channels  through  which  the  matters  organized  in  the 
foliage  most  abundantly  pass  in  their  downward  move 
ment  to  nourish  the  stem  and  root.  Fig.  55  representg 


THE    VEGETATIVE    ORGANS    OF    PLANTS. 


281 


the  sieve-cells  in  the  overground  stem  of  the  potato ;  A, 
J2,  cross-section  of  parts  of  vascular  bundle — -4,  exterior 
part  towards  rind ;  J5,  interior  portion  next  to  pith- 
cell-tissue  inclosing 

sieve- 

which  a 

turbid 


the     smaller 
cells,  A,    B, 
contain    sap 
with    minute    gran 
ules  ;      £,    cambium 
cells  \   c,   wood-cells 
(which  are  absent  in 
the  potato  tuber ;)  d,   ^ 
ducts     intermingled 
with  wood-cells.     C 
represents  a  section 
lengthwise     of    the 
sieve-ducts;  and  D^ 
more  highly  magni- 
fied,exhibits  the  fine 
ly  perforated,  trans-  d 
verse          partitions, 
through    which    the 

O 

liquid  contents  free 
ly  pass. 

Milk  Ducts,— Be-  a 
sides  the  ducts  al 
ready  described, 
there  is,  in  many 
plants,  a  system  of 
irregularly  branched 
channels  containing 
a  milky  juice,  as  in  the  sweet  potato,  dandelion,  milk 
weed,  etc.  These  milk-ducts,  together  with  many  other 
details  of  stem-structure,  are  imperfectly  understood,  and 
require  no  further  notice  in  this  treatise. 

Herbaceous   Stems* — Annual  stems   of   the  exogenous 


55. 


282  HOW    CROPS    GROW. 

kind,  whose  growth  is  entirely  arrested  by  winter,  consist 
usually  of  a  single  ring  of  woody  tissue  with  interior 
pith  and  surrounding  bark.  Often,  however,  the  zone  of 
wood  is  thin,  and  possesses  but  little  solidity,  while  the 
chief  part  of  the  stem  is  made  up  of  cell-tissue,  so  that  the 
stem  is  herbaceous. 

Woody  Stems* — Perennial  exogenous  stems  consist,  in 
temperate  climates,  of  a  series  of  rings  or  zones,  corre 
sponding  in  number  with  that  of  the  years  during  which 
their  growth  has  been  progressing.  The  stems  of  our 
shrubs  and  trees,  especially  after  the  first  few  years  of 
growth,  consist,  for  the  most  part,  of  woody  tissue,  the  pro 
portion  of  cell-tissue  being  very  small. 

The  annual  cessation  of  growth  which  occurs  at  the 
approach  of  winter,  is  marked  by  the  formation  of  smaller 
or  finer  wood-cells,  as  shown  in  fig.  54,  while  the  vigorous 
renewal  of  activity  in  the  cambium  at  spring-time  is  ex 
hibited  by  the  growth  of  larger  cells,  and  in  many  kinds 
of  wood  in  the  production  of  ducts,  which,  as  in  the  oak, 
are  visible  to  the  eye  at  the  interior  of  the  annual  layers. 

Sap-wood  and  Heart- wood, — The  living  processes  in 
perennial  stems,  while  proceeding  with  most  force  in  the 
cambium,  are  not  confined  to  that  locality,  but  go  on  to  a 
considerable  depth  in  the  wood.  Except  at  the  cambial 
layer,  however,  these  processes  consist  not  in  the  forma 
tion  of  new  cells,  nor  the  enlargement  of  those  once  form 
ed — not  properly  in  growtli — but  in  the  transmission  of 
sap  and  the  deposition  of  organized  matter  on  the  interior 
of  the  wood-cells.  In  consequence  of  this  deposition  the 
inner  or  heart-wood  of  many  of  our  forest  trees  becomes 
much  denser  in  texture  and  more  durable  for  industrial 
purposes.  It  then  acquires  a  color  different  from  the  outer 
or  sap-wood  (alburnum,)  becomes  brown  in  most  cases, 
though  it  is  yellow  in  the  barberry  and  red  in  the  red 
cedar. 


THE    VEGETATIVE    ORGANS    OF   PLANTft.  28S 

The  final  result  of  the  filling  up  of  the  cells  of  the  heart- 
wood  s  to  make  this  part  of  the  stem  almost  or  quite  im 
passable  to  sap,  so  that  the  interior  wood  may  be  removed 
by  decay  without  disturbing  the  vigor  of  the  tree. 

Passage  of  Sap  through  the  Stem,—  The  stem,  besides 
supporting  the  foliage,  flowers,  and  fruit,  has  also  a  most 
important  office  in  admitting  the  passage  upward  to  these 
organs,  of  the  water  and  mineral  matters  which  enter  the 
plant  by  the  roots.  Similarly,  it  allows  the  downward 
transfer  to  the  roots,  of  substances  gathered  by  the  foliage 
from  the  atmosphere.  To  this  and  other  topics  connected 
with  the  ascent  and  descent  of  the  sap  we  shall  hereafter 
recur. 

The  stem  constitutes  the  chief  part  by  weight  of  many 
plants,  especially  of  forest  trees,  and  serves  the  most  im 
portant  uses  in  agriculture,  as  well  as  in  a  thousand  other 
industries. 


LEAVES. 

These  most  important  organs  issue  from  the  stem,  are 
at  first  folded  curiously  together  in  the  bud,  and  after 
wards  expand  so  as  to  present  a  great  amount  of  surface 
to  the  air  and  light. 

The  leaf  consists  of  a  thin  membrane  of  cell-tissue,  ar 
ranged  upon  a  skeleton  or  net-work  of  fibers  and  ducts. 
It  is  directly  connected  with,  and  apparently  proceeds 
from,  the  cambial-layer  of  the  stem,  of  which  it  may,  ac 
cordingly,  be  considered  an  expansion. 

In  certain  plants,  as  the  cactus  (prickly  pear),  there 
scarcely  exist  any  leaves,  or,  if  any  occur,  they  do  not 
differ,  except  in  external  form,  from  the  stems.  Many  of 
these  plants,  above  ground  are  in  form,  all  stem,  while  in 
structure  and  function,  they  are  all  lea£ 


*:J84  HOW    CROPS    GROAV. 

In  the  grasses,  although  the  stem  and  leaf  are  distinguish 
able  in  shape,  they  are  but  little  unlike  in  other  external 
characters. 

In  forest  trees,  \ve  find  the  most  obvious  and  striking 
differences  between  the  stem  and  leaves. 

Green  C olor  Of  Leaves. — A  peculiarity  most  character 
istic  of  the  leaf,  so  long  as  it  is  in  vigorous  discharge  of 
its  proper  vegetative  activities,  is  the  possession  of  a  green 
color.  This  color  is  also  proper  in  most  cases  to  the  young 
bark  of  the  stem,  a  fact  further  indicating  the  connection 
between  these  parts,  or  rather  demonstrating  their  identity 
of  origin  and  function,  for  it  is  true,  not  only  in  the  case 
of  the  cactuses,  but  also  in  that  of  all  other  young  plants, 
that  the  green  (young)  stems  perform,  to  some  extent,  the 
same  offices  as  the  leaves. 

The  loss  of  green  color  that  occurs  in  autumn,  in  case 
of  the  foliage  of  our  deciduous  trees,  or  on  the  maturing 
of  the  plant  in  case  of  the  cereal  grains,  is  connected  with 
the  cessation  of  growth  and  death  of  the  leaf. 

There  are  plants  whose  foliage  has  a  red,  brown,  white,  or  other  than 
a  green  color  daring  the  period  of  active  growth.  Many  of  these  are 
cultivated  by  florists  for  ornamental  purposes.  The  cells  of  these  color 
ed  leaves  are  by  no  means  destitute  of  chlorophyll,  as  is  shown  by  mi 
croscopic  examination,  though  this-substance  is  associated  with  other 
coloring  matters  which  mask  its  green  tint. 

Structure  Of  Leaves, — While  in  shape,  size,  modes  of 
arrangement  upon,  and  attachment  to  'the  stem,  we  find 
among  leaves  no  end  of  diversity,  there  is  great  simplicity 
in  the  matter  of  their  internal  structure. 

The  whole  surface  of  the  leaf,  on  both  sides,  is  covered 
with  epidermis,  a  coating,  which,  in  many  cases,  may  be 
readily  stripped  off  the  leaf,  and  consists  of  thick- walled 
cells,  which  are,  for  the  most  part,  devoid  of  liquid  con 
tents,  except  when  very  young.  (E,  E,  fig.  56.) 

The  accompanying  figure  (56)  represents  the  appearance  of  a  bit  of 
bean-leaf  as  seen  on  a  section  from  the  upper  to  the  lower  surface  and 
highly  magnified. 


THE    VEGETATIVE    ORGANS    OF    PLANTS.  285 

Below  the  upper  epidermis,  there  often  occur  one  or 
more  layers  of  oblong  cells,  whose  sides  are  in  close  con 
tact,  and  which  are  arranged  endwise,  with  reference  to 
the  flat  of  the  leaf.  Below  these,  down  to  the  lower  epi 
dermis,  for  one-half  to  three-quarters  of  the  'thickness  of 
the  leaf,  the  cells  are  commonly  spherical  or  irregular  in 
figure  and  arrangement,  and  more  loosely  disposed,  with 
numerous  and  large  interspaces. 

The  interspaces  among  the  leaf-cells  are  occupied  with  air, 
which  is  also,  in  most  cases,  the  only  con 
tent  of  the  epidermal  cells.  The  active 
cells  of  the  leaf  contain  some  or  all  of  the 
various  proximate  principles  which  have 
been  already  noticed,  and  in  addition 
the  coloring  matter  of  vegetation,  — the 

o  o 

so-called  chlorophyll,  or  leaf-green,  p. 
109.  Under  the  microscope,  this  sub 
stance  is  commonly  seen  in  the  form 
of  minute  grains  attached  to  the  walls 
of  the  cells,  as  in  fig.  56,  or  coating 
starch  granules,  or  else  floating  free  in  FU.  5o 

the  cell-sap. 

The  structure  of  the  veins  or  ribs  of  the  leaf  is  similar 
to  that  of  the  vascular  bundles  or  fibers  of  the  stem,  of 
which  they  are  branches.  At  «,  fig.  56,  is  seen  the  cross 
section  of  a  vein  in  the  bean-leaf. 

The  epidermis,  while  often  smooth,  is  frequently  beset 
with  hairs  or  glands,  as  seen  in  the  figure.  These  are  va 
riously  shaped  cells,  sometimes  empty,  sometimes,  as  in 
the  nettle,  filled  with  a:i  acid  liquid.  Their  office  is  little 
understood. 

Leaf-Pores. — The  epidermis  is  further  provided  with  a 
vast  number  of  curious  "  breathing  pores,"  or  stomata,  by 
means  of  which-  the  intercellular  spaces  in  the  interior  of 
the  leaf  may  be  brought  into  direct  communication  with 
the  outer  atmosphere.  Each  <;f  these  stomata  consists 


286 


HOW    CROPS    GROW. 


Fig.  57. 


usually  of  two  curved  cells,  which  are  disposed  toward 
each  other  nearly  like  the  two  sides  of  the  letter  O,  or  like 
the  halves  of  an  elliptical  carriage-spring,  (figs.  52  and  53). 

The  opening  between  them 
is  an  actual  orifice  in  the 
skin  of  the  leaf.  The  size  of 
the  orifice  is,  however,  con 
stantly  changing,  as  the  at 
mosphere  becomes  drier  or 
more  moist,  and  as  the  sun 
light  acts  more  or  less  in 
tensely  on  its  surface.  In 
moist  air,  they  curve  out 
wards,  and  the  aperture  is 
enlarged;  in  dry  air,  they  straighten  and  shut  together 
like  the  springs  of  a  heavily  loaded  carriage,  and  nearly 
or  entirely  close  the  entrance.  The  effect  of  strong  light 
is  to  enlarge  their  orifices. 

In  flu:.  50  is  represented  a  section  through  the  shorter  diameter  of  a 
pore  on  the  under  surface  of  a  bean-leaf.  The  air-space  within  it  is 
shaded  black.  Unlike  the  other  epidermal  cells,  those  of  the  leaf-pore 
contain  grains  of  chlorophyll. 

Fig.  57  represents  a  portion  of  the  epidermis  of  the  upper  surface  of 
a  potato-leaf,  and  fig.  58  a  similar  portion  of  the  under  surface  of  the  same 
leaf,  magnified  200  diameters.  In  both  figures  are  seen  the  open  pores 
between  the  semi-elliptical  cells.  The  outline  of  the  other  epidermal 
cells  is  marked  by  irregular  double  lines. 
The  round  bodies  in  the  cells  of  the 
pores  are  starch-grains,  often  present 
iu  these  cells,  when  not  existing  in  any 
other  part  of  the  leaf. 

The  stomata  are  with  few  ex 
ceptions  altogether  wanting  on 
the  submerged  leaves  of  nquntic 
pl:i nt s.  On  floating  leaves  they 
occur,  but  only  on  the  upper 
surface.  Thus,  as  a  rule,  they 

arc  not  fmun1  in  contact  with  liquid  water.     On  the  other 
hand,  they  are  either  absent  from,  or  comparatively  few  in 


THE   VEGETATIVE    ORGANS    OF   PLANTS.  287 

number  upon,  the  upper  surfaces  of  land  plants,  which  are 
exposed  to  the  heat  of  the  sun,  while  they  exist  in  great 
numbers  on  the  lower  sides  of  all  green  leaves.  In  number 
and  size,  they  vary  remarkably.  Some  leaves  possess  but 
800  to  the  square  inch,  while  others  have  as  many  as 
170,000  to  that  amount  of  surface.  About  100,000  may 
be  counted  on  an  average-sized  apple-leaf.  In  general, 
they  are  largest  and  most  numerous  on  plants  which  be 
long  in  damp  and  shaded  situations,  and  then  exist  on 
both  sides  of  the  leaf. 

The  epidermis  itself  is  most  dense— consists  of  thick- 
walled  cells  and  several  layers  of  them — in  case  of  leaves 
which  belong  to  the  vegetation  of  sandy  soils  in  hot  cli 
mates.  Often  it  is  impregnated  with  wax  on  its  upper 
surface,  and  is  thereby  made  almost  impenetrable  to  moist- 
ure.  On  the  other  hand,  in  rapidly  growing  plants  adapt 
ed  to  moist  situations,  the  epidermis  is  thin  and  delicate. 

Exhalation  of  Water-Vapor, — A  considerable  loss  of 
water  goes  on  from  the  leaves  of  growing  plants  when 
they  are  freely  exposed  to  the  atmosphere.  The  water 
thus  lost  exhales  in  the  form  of  invisible  vapor.  The 
quantity  of  water  exhaled  from  any  plant  may  be  easily 
ascertained,  provided  it  is  growing  in  a  pot  of  glazed 
earthen,  or  other  impervious  material.  A  metal  or  glass 
cover  is  cemented  air-tight  to  the  rim  of  the  vessel,  and 
around  the  stem  of  the  plant.  The  cover  has  an  opening 
with  a  cork,  through  which  weighed  quantities  of  water 
are  added  from  time  to  time,  as  required.  The  amount 
of  exhalation  during  any  given  interval  of  time  is  learned 
with  a  close  approach  to  accuracy  by  simply  noting  the 
loss  of  weight  which  the  plant  and  pot  together  suffer. 
Hales,  who  first  experimented  in  this  manner,  found  that 
a  sunflower,  whose  foliage  had  an  aggregate  surface  of 
39  square  feet,  gave  off  3  Ibs.  of  water  in  a  space  of  24 
hours.  Knop  observed  a  maize-plant  to  exhale,  bet  weep 


288  HOW   CROPS    GROW. 

May  22d  and  September  4th,  no  less  than  36  times  ita 
weight  of  water. 

Exhalation  is  not  a  regular  or  uniform  process,  but  varies 
with  a  number  of  circumstances  and  conditions.  It  de 
pends  largely  upon  the  dryness  and  temperature  of  the 
air.  When  the  air  is  in  the  state  most  favorable  to 
evaporation,  thr  loss  from  the  plant  is  rapid  and  large. 
When  the  air  is  saturated  with  moisture,  as  during  dewy 
nights  or  rainy  weather,  then  exhalation  is  nearly  or 
totally  checked. 

The  temperature  of  the  soil,  and  even  its  chemical  com 
position,  the  condition  of  the  le:if  as  to  its  age,  texture, 
and  number  of  stomata,  likewise  affect  the  rate  of  ex 
halation. 

Exhalation  is  a  process  not  necessary  to  the  life  of  the 
plant,  since  it  may  be  suppressed  or  be  reduced  to  a 
minimum,  as  in  a  Wardian  case  or  fernery,  without  evident 
influence  on  growth.  Neither  is  it  detrimental,  unless  the 
loss  is  greater  than  the  supply.  If  water  escapes  from  the 
leaves  faster  than  it  enters  the  roots,  the  plant  wilts ;  and 
if  this  disturbance  goes  on  too  far,  it  dies. 

Exhalation  ordinarily  proceeds  to  a  large  extent  from 
the  surface  of  the  epidermal  cells.  Although  the  cavities 
of  these  cells  are  chiefly  occupied  with  air,  their  thickened 
walls  transmit  outward  the  water  which  is  supplied  to 
the  interior  of  the  leaf  through  the  carnbial  ducts.  Other 
wise  the  escape  of  vapor  occurs  through  the  stomata.  These 
pores  appear  to  have  the  function  of  regulating  the  exhala 
lion,  to  a  great  extent,  by  their  property  of  closing,  when 
the  air,  from  its  dryness,  favors  rapid  evaporation.  They 
Are,  in  fact,  self-acting  valves  which  protect  the  plant  from 
tco  sudden  and  rapid  loss  of  water. 

Access  of  Air  to  the  Interior  of  the  Plant,— Not  only 
does  the  leaf  allow  the  escape  of  vapor  of  water,  but  it 
admits  of  the  entrance  and  exit  of  gaseous  bodies. 


THE   VEGETATIVE    ORGANS    OF    PLANTS. 


289 


The  particles  of  atmospheric  air  have  easy  access  to  the 
interior  of  all  leaves,  however  dense  and  close  their  epi 
dermis  may  be,  however  few  or  small  their  stomata.  All 
leaves  are  actively  engaged  in  absorbing  and  exhaling  cer 
tain  gaseous  ingredients  of  the  atmosphere  during  the 
whole  of  their  healthy  existence. 

The  entire  plant  is,  in  fact,  pervious  to  air  through  the 
stomata  of  the  leaves.  These  com 
municate  with  the  intercellular 
spaces  of  the  leaf,  which  are,  in 
general,  occupied  exclusively  with 
air,  and  these  again  connect  with 
the  ducts  which  ramify  throughout 
the  veins  of  the  leaf  and  branch 
from  the  vascular  bundles  of  the 
stem.  In  the  bark  or  epidermis  of 
woody  stems,  as  Hales  long  ago 
discovered,  pores  or  cracks  exist, 
through  which  the  air  has  communi 
cation  with  the  longitudinal  ducts. 

These  facts  admit  of  demonstration  by 
simple  means.  Sachs  employs  for  this  pur 
pose  an  apparatus  consisting  of  a  short  wide 
tube  of  glass,  B,  fig.  59,  to  which  is  adapted, 
below,  by  a  tightly  fitting  cork,  a  bent  glass 
tube.  The  stem  of  a  leaf  is  passed  through 
a  cork  which  is  then  secured  air-tight  in  the 
other  opening  of  the  wide  tube,  the  leaf  itself 
being  included  in  the  latter,  and  the  joints 
are  made  air-tight  by  smearing  with  tallow. 
The  whole  is  then  placed  in  a  glass  jar  con 
taining  enough  water  to  cover  the  projecting  leaf-stem,  and  mercury  is 
quickly  poured  into  the  open  end  of  the  bent  tube,  so  as  nearly  to  fill  the 
latter.  The  pressure  of  the  column  of  this  dense  liquid  immediately  forces 
air  into  the  stomata  of  the  leaf,  and  a  corresponding  quantity  is  forced  on 
through  the  intercellular  spaces  and  through  the  vein  ducts  into  the 
ducts  of  the  leaf-stem,  whence  it  issues  in  fine  bubbles  at  &  It  is  even 
easy  in  many  cases  to  demonstrate  the  permeability  of  the  leaf  to  air  by 
immersing  it  in  water,  and,"  taking  the  leaf-stem  between  the  lip?,  produce 
a  current  by  blowing.  In  this  case  the  air  escapes  from  the  stomata. 
The  air-passages  of  the  stem  may  be  shown  by  a  similar  arrangement, 

13 


290  now  CROPS  GROW. 

or  in  many  instances,  as,  for  example,  with  a  stalk  of  maize,  by  sirnplj 
immersing  one  end  in  water  and  blowing  into  the  other. 

On  the  contrary,  roots  are  destitute  of  any  visible 
pores,  and  are  not  pervious  to  external  air  or  vapor  in  the 
sense  that  leaves  and  young  stems  are. 

The  air  passages  in  the  plant  correspond  roughly  to  the 
mouth,  throat,  and  breathing  cavities  of  the  animal.  We 
have,  as  yet,  merely  noticed  the  direct  communication  of 
these  passages  with  the  external  air  by  means  of  micros 
copically  visible  openings.  But  the  cells  which  are  not 
visibly  porous  readily  allow  the  access  and  egress  of  wa 
ter  and  of  gases  by  osmose.  T_o  the  mode  in  which  this 
is  effected  we  shall  recur  on  subsequent  pages,  (pp.  354  - 
86. 


Offices  Of  Foliage  are  to  put  the  plant  in  commu 
nication  with  the  atmosphere  and  with  the  sun.  On  the 
one  hand  it  permits,  and  to  a  certain  degree  regulates,  the 
escape  of  the  water  which  is  continually  pumped  into  the 
plant  by  its  roots,  and  on  the  other  hand  it  absorbs  from 
tho  air,  which  freely  penetrates  it,  certain  gases  which 
furnish  the  principal  materials  for  the  organization  of  vege 
table  matter.  We  have  seen  that  the  plant  consists  of 
elements,  some  of  which  are  volatile  at  the  heat  of  ordina 
ry  fires,  while  others  are  fixed  at  this  temperature.  When 
a  plant  is  burned,  the  former,  to  the  extent  of  90-99  per 
cent  of  the  plant,  are  converted  into  gases,  the  latter  re' 
main  as  ashes. 

The  reconstruction  of  vegetation  from  the  products  of 
its  combustion  (or  decay)  is,  in  its  simplest  phase,  the 
gathering  by  a  new  plant  of  the  ashes  from  the  soil 
through  its  roots,  and  of  these  gases  from  the  air  by  its 
leaves,  and  the  compounding  of  these  comparatively  sim 
ple  substances  into  the  highly  complex  ingredients  of  the 
vegetable  organism.  Of  this  work  the  leaves  have  by  far 
the  larger  share  to  perform;  hence  the  extent  of  their  sur 
face  and  their  indispensability  to  the  welfare  of  the  plant 


REPRODUCTIVE    ORGANS    OI    PLANTS.  291 

The  assimilation  of  carbon  in  the  plant  is  most  inti 
mately  connected  with  the  chlorophyll,  which  has  been  no 
ticed  as  the  green  coloring  matter  of  the  leaf,  and  depends 
also  upon  the  solar  rays. 


CHAPTER    IY. 
REPRODUCTIVE    ORGANS    OF    PLANTS. 

§1- 

THE    FLOWER. 

The  onward  growth  of  the  stem  or  of  its  branches  is 
not  necessarily  limited,  until  from  the  terminal  buds,  in 
stead  of  leaves,  only  FLOWERS  unfold.  When  this  happcMis, 
as  is  the  case  with  most  annual  and  biennial  plants,  raised 
on  the  farm  or  in  the  garden,  the  vegetative  energy  has  usu 
ally  attained  its  fullest  development,  and  the  reproductive 
function  begins  to  prepare  for  the  death  of  the  individual 
by  providing  seeds  which  shall  perpetuate  the  species. 

There  is  often  at  first  no  apparent  difference  between 
the  leaf-buds  and  flower-buds,  but  commonly  in  the  later 
stages  of  their  growth,  the  latter  are  to  be  readily  dis 
tinguished  from  the  former  by  their  greater  size,  and  by 
peculiar  shape  or  color. 

The  Flower  is  a  short  branch,  bearing  a  collection  of 
orgnns,  which,  though  usually  having  little  resemblance 
to  foliage,  may  be  considered  as  leaves,  more  or  less  mod 
ified  in  form,  color,  and  office. 

The  flower  commonly  presents  four  different  sets  of  or 
gans,  viz ,  Calyx,  Corolla,  Stamens,  and  Pistils,  and  is 
then  said  to  be  complete,  as  in  case  of  the  apple,  potato 


292 


HOW    CROPS    GllOW. 


rt 


and  many  common  plants.  Fig.  60  represents  the  com 
plete  flower  of  the  Fuchsia,  or  ladies'  ear-drop,  now  uni 
versally  cultivated.  In  fig.  61  the  same  is  shown  in 
section. 

The  Calyx,  (cup,)  ex,  is  the  outermost  floral  envelope. 
Its  color  is  red  or  white  in  the  Fuchsia,  though  generally 
it  is  green.  When  it  consists  of  several  distinct  leaves, 
they  are  called 
sepals.  The  calyx 
is  frequently  small 
and  inconspicuous. 
In  some  cases  it 
falls  away  as  the 
flower  opens.  In 
the  Fuchsia  it  firm 
ly  adheres  at  its 
base  to  the  seed- 
vessel,  and  is  divid 
ed  into  four  lobes. 
The  Corolla, 
(crown,)  c',  or  ca> 
is  one  or  several 
series  of  leaves 
which  are  situated 
within  the  calyx. 
It  is  usually  of  some  other  than  a  green  color,  (in  the  Fuchsia, 
purple,  etc.,)  often  has  marked  peculiarities  of  form  and 
great  delicacy  of  structure,  and  thus  chiefly  gives  beauty 
to  the  flower.  When  the  corolla  is  divided  into  separate 
leaves,  these  are  termed  petals.  The  Fuchsia  has  four 
petals,  which  are  attached  to  the  calyx-tube. 

The  Stamens,  3,  in  fig's  60  and  61,  are  generally  slender, 
thread-like  organs,  terminated  by  an  oblong  sack,  the  an 
ther,  which,  when  the  flower  attains  its  full  growth,  dis 
charges  a  fine  yellow  or  brown  dust,  the  so-called  pollen. 


st 


Fig.  60. 


Fig.  61. 


REPRODUCTIVE    ORGANS    OF   PLANTS.  29S 

The  forms  of  anthers,  as  well  as  of  the  grains  of  pollen,  vary  with  ne»ilv 
erery  kind  of  plant.  The  yellow  pollen  of  pine  and  spruce  trees  is  not 
infrequently  transported  by  the  wind  to  a  great  distance,  and  when 
brought  down  by  rain  in  considerable  quantities,  has  been  mistaken  for 
sulphur. 

The  Pistil,  p,  in  fig's  60  and  61,  or  pistils,  occupy  the 
center  of  the  perfect  flower.  They  are  exceedingly  va 
rious  in  form,  but  always  have  at  their  base  the  seed-ves 
sels  or  ovaries,  ov,  in  which  are  found  the  ovules  (little 
eggs)  or  rudimentary  seods.  The  summit  of  the  pistil  is 
destitute  of  the  epidermis  which  covers  all  other  parts  of 
the  plant,  and  is  termed  the  stigma,  st. 

As  has  been  remarked,  the  floral  organs  may  be  consid 
ered  to  be  modified  leaves ;  or  rather,  all  the  appendages 
of  the  stem — the  leaves  and  the  parts  of  the  flower  to 
gether — are  different  developments  of  one  fundamental 
organ. 

The  justness  of  this  idea  is  sustained  by  the  transforma 
tions  which  are  often  observed. 

The  rose  in  its  natural  state  has  a  corolla  consisting  of 
five  petals,  but  has  a  multitude  of  stamens  and  pistils.  In 
a  rich  soil,  or  as  the  effect  of  those  agencies  which  are 
united  in  "  cultivation,"  nearly  all  the  pistils  and  stamens 
lose  their  reproductive  function  and  proper  structure,  and 
revert  to  petals ;  hence  the  flower  becomes  double.  The 
tulip,  poppy,  and  numerous  garden-flowers,  illustrate  this 
interesting  metamorphosis,  and  in  these  flowers  we  may 
often  see  at  once  the  change  in  various  stages  intermediate 
between  the  perfect  petal  and  the  unaltered  pistil. 

On  the  other  hand,  the  reversion  of  all  the  floral  organs 
into  ordinary  green  leaves  has  been  observed  not  infre 
quently,  in  case  of  the  rose,  white  clover,  and  other 
plants. 

While  the  complete  flower  consists  of  the  four  sets  of 
organs  above  described,  only  th^  stamens  and  pistils  are 
essential  to  the  production  of  see  1.  The  latter,  accord* 


294  HOW    CROPS    GKOW. 

ingly,  constitute  A  perfect  flower  even  in  the  absence  of 
calyx  and  corolb,. 

The  flower  of  buckwheat  has  no  corolla,  but  a  white  or 
pinkish  calyx. 

The  grasses  h'.ve  flowers  in  which  calyx  and  corolla  are 
represented  by  scale-like  leaves,  which,  as  the  plants  mr 
',ure,  become  cl1  aff. 

In  various  r;hnts  the  stamens  and  pistils  are  borne  . 
'parate  f.owers.     Such  are  called  monoecious  plants,  ot 

hioh  the  (wrch  and  oak,  maize,  melon,  squash,  cucumber, 
;nd  ofte-jVr.es  the  strawberry,  are  examples. 

In  cas'  of  maize,  the  staminate  flowers  are  the  "tas 
sels'"  at  the  summit  of  the  stalk;  the  pistillate  flowers 
are  If/ft  young  ears,  the  pistils  themselves  being  the  "  silk," 
each  fiber  of  which  has  an  ovary  at  its  base,  that,  if  fer 
tilized,  developes  to  a  kernel. 

Dioecious  plants  are  those  which  bear  the  staminate 
(rrale,  or  sterile)  flowers  and  the  pistillate  (female,  or  fer 
tile)  flowers  on  different  individuals;  the  willow  tree,  tho 
hop-vine,  and  hemp,  are  of  this  kind. 

Fertilization  and  Fructification, — The  grand  function 
of  tho  flower  i^,  fructification.  For  this  purpose  the  pollen 
must  fall  upon  or  be  carried  by  wind,  insects,  or  other  agen 
cies,  to  the  naked  tip  of  the  pistil.  Thus  situated,  each 
pollen-grain  sends  out  a  slender  tube  of  microscopic  diam 
eter,  which  penetrates  the  interior  of  the  pistil  until  it  en 
ters  the  seed-sack  and  comes  in  contact  with  the  ovule  or 
rudimentary  sood.  This  contact  being  established,  the 
ovule  is  fertilized  and  begins  to  grow.  Thenceforward 
the  corolla  and  stamens  usually  wither,  while  the  base  of 
the  pistil  and  the  included  ovules  rapidly  increase  in  size 
until  the  seeds  are  ripe,  when  the  seed-vessel  falls  to  the 
ground  or  else  opens  and  releases  its  contents. 

Fi<j:.  02  exhibits  the  process  of  fertilization  as  observed 
in  a  plant  allied  to  buckwheat,  viz.,  the  Potygonum  con' 


REPRODUCTIVE    ORGANS    OF    PLANTS. 


295 


volvulus.  The  cut  represents  a  magnified  section  length- 
Aviso  through  the  short  pistil ;  a,  is  the  stigma  or  summit 
of  the  pistil;  5,  are  grains  of  pollen ;  c,  are  pollen  tubes 
that  have  penetrated  into  the  seed- 
vessel  which  forms  the  base  of  the 
pistil;  one  lias  entered  the  mouth  of 
the  rudimentary  seed,  </,  and  reached 
tlie  embryo  sack,  e,  within  which  it 
causes  the  development  of  a  germ ;  d, 
represents  the  interior  wall  of  the 
seed-vessel ;  A,  the  base  of  the  seed 
and  its  attachment  to  the  seed-vessel. 

Darwin  has  shown  that  certain 
plants,  which  have  pistils  and  stamens 
in  the  same  flower,  are  incapable  of 
self-fertilization,  and  depend  upon  in 
sects  to  carry  pollen  to  their  stigmas. 
Such  are  many  Orchids. 

Artificial  Fecundation  has  been 
proposed  by  Hooibrenk,  in  Belgium, 
as  a  means  of  increasing  the  yield  of  certain  crops.  Hooi. 
brenk's  plan  of  agitating  the  heads  of  grain  at  the  time 
when  the  pollen  is  ripe,  in  order  to  ensure  its  distribution, 
which  is  done  by  two  men  traversing  the  field  carrying  a 
rope  between  them  so  as  to  lightly  brush  over  the  heads, 
appears  to  have  been  found  very  useful  in  some  cases, 
though  in  many  trials  no  good  effects  have  followed  its 
application.  We  must  therefore  conclude  that  agitation 
by  the  winds  and  the  good  oflices  of  insects  commonly 
render  artificial  assistance  in  the  fecundating  process  en 
tirely  superfluous. 

Hybridizing. — As  the  union  of  the  sexes  of  different 
kinds  of  animals  sometimes  results  in  the  birth  of  a  hybrid, 
so  among  plants,  the  ovules  of  one  kind  may  be  fertilized 
by  the;  pollen  of  another,  and  the  seed  thus  developed,  in 
its  growth,  produces  a  hybrid  plant.  In  both  the  animal 


296  HOW   CROPS   GROW. 

and  vegetable  kingdoms  the  limits  within  which  hybridiza 
tion  is  possible  appear  to  be  very  narrow.  It  is  only  be 
tween  closely  allied  species  that  fecundation  can  take  place. 
Wheat,  oats,  and  barley,  show  no  tendency  to  "  mix  "  ;  the 
pollen  of  one  of  these  similar  plants  being  incapable  of 
fertilizing  the  ovules  of  the  others. 

In  flower  and  fruit-culture,  hybridization  is  practised  or 
attempted,  as  a  means  of  producing  new  kinds.  .Thus  the 
celebrated  Rogers'  Seedling  Grapes  are  believed  to  be  hy 
brids  between  the  European  grape,  Vitis  vinifera,  and 
the  allied  but  distinct  Vitis  labni&ca,  of  North  America. 

Hybridization  between  plants  is  effected,  if  at  all,  by 
removing  from  the  flower  of  one  kind,  the  stamens  before 
they  shed  their  pollen,  and  dusting  the  summit  of  the  pistil 
with  pollen  from  another  kind. 

The  mixing  of  different  varieties,  as  commonly  happens 
among  maize,  melons,  etc.,  is  not  properly  hybridization, 
this  word  being  used  in  the  long-established  sense.  Wo 
are  thus  led  to  brief  notice  of  the  meaning  of  the  terms 
species  and  variety,  and  of  the  distinctions  employed  in 
botanical  classification. 

Species. — The  idea  of  species  as  distinct  from  variety 
which  has  been  held  by  most  scientific  authorities  hither 
to,  is  based  primarily  on  the  faculty  of  continued  repro 
duction.  The  horse  is  a  species  comprising  many  vari 
eties.  Any  two  of  these  varieties  by  sexual  union  may 
propagate  the  species.  The  same  is  true  of  the  ass.  The 
horse  and  the  ass  by  sexual  union  produce  a  hybrid — the 
mule, — but  the  sexual  union  of  mules  is  without  result. 
They  cannot  continue  the  mule  as  a  distinct  kind  of  ani 
mal — as  a  species.  Among  animals  a  species  therefore  com 
prises  all  those  individuals  which  are  related  by  common 
origin  or  fraternity,  and  which  are  capable  of  sexual  fer 
tility.  This  conception  involves  original  and 
differences  between  different  species. 


REPRODUCTIVE    ORGANS    OF   PLANTS.  29? 

Species,  therefore,  cannot  change  any  of  their  essential 
characters,  those  characters  which  are  hence  termed  specific. 

Varieties. — Individuals  of  the  same  species  differ.  In 
fact,  no  two  individuals  are  quite  alike.  Circumstances  of 
temperature,  food,  and  habits  of  life,  increase  these  differ 
ences,  and  varieties  originate  when  such  differences  assume 
a  comparative  permanence  and  fixity.  But  as  external 
conditions  cause  variation  away  from  any  particular  rep 
resentative  of  a  species,  so  they  may  cause  variation  back 
again  to  the  original,  and  although  variation  may  take  a 
seemingly  wide  range,  its  bounds  are  fixed  and  do  not 
touch  specific  characters. 

The  causes  that  produce  varieties  are  numerous,  but  in 
many  cases  their  nature  and  their  mode  of  action  is  diffi 
cult  or  impossible  to  understand.  The  influence  of  scarcity 
or  abundance  of  nutriment  we  can  easily  comprehend  may 
dwarf  a  plant  or  lead  to  the  production  of  a  giant  indi 
vidual  ;  but  how,  in  some  cases,  the  peculiarities  thus  im 
pressed  upon  individuals  acquire  permanence  and  are 
transmitted  to  subsequent  generations,  while  in  others 
they  disappear,  is  beyond  explanation. 

Among  plants,  varieties  may  often  be  perpetuated  by 
the  seed.  This  is  true  of  our  cereal  and  leguminous 
plants,  which  reproduce  their  kind  with  striking  regulari 
ty.  Other  plants  cannot  be  or  are  not  reproduced  unalter 
ed  by  the  seed,  but  are  continued  in  the  possession  of  their 
peculiarities  by  cuttings,  layers,  and  grafts.  Here  the  in 
dividual  plant  is  in  a  sense  divided  and  multiplied.  The 
species  is  propagated,  but  not  reproduced.  The  fact  that 
the  seeds  of  a  potato,  a  grape,  an  apple,  or  pear,  cannot  be 
depended  upon  to  reproduce  the  variety,  may  perhaps  be 
more  commonly  due  to  unavoidable  contact  of  pollen 
from  other  varieties,  than  to  inability  of  the  mother  plant 
to  perpetuate  its  peculiarities.  That  such  inability  often 
exists,  is,  however,  well  established,  and  is,  in  general, 
most  obvious  in  case  of  varieties  that  have  to  the  greatest 
13* 


298  HOW   CROPS    GROW. 

degree  departed  from  the  original  specific  type.  Thus 
nature  puts  the  same  limit  to  variation  within  a  species 
that  she  has  established  against  the  mixing  of  species. 

Darwin's  Hypothesis,  which  is  now  accepted  by  many 
naturalists,  is  to  the  effect  that  species,  as  above  defined, 
do  not  exist,  but  that  new  kinds  (so-called  species)  of  ani 
mals  and  plants  may  arise  by  variation,  and  that  all  exist 
ing  animals  and  plants  may  have  developed  by  a  process 
of  "  natural  selection  "  from  one  original  type.  Our  ob 
ject  here  is  not  to  discuss  this  intricate  question,  but  sim 
ply  to  put  the  reader  in  possession  of  the  meaning  attach, 
ed  to  the  terms  currently  employed  in  science — termF 
which  must  long  continue  in  use  and  which  are  necessarily 
found  in  these  pages.* 

Genus,  (plural  Genera.) — In  the  language  of  anti-Dar- 
winianism,  any  set  of  oaks  that  are  capable  of  reproducing 
their  kind  by  seed,  but  cannot  mix  their  seed  with  other 
oaks,  constitute  a  species.  Thus,  the  white  oak  is  one 
species,  the  red  oak  is  another,  the  water  oak  is  a  third, 
the  live  oak  a  fourth,  and  so  on.  All  the  oaks,  white,  red, 
etc.,  taken  together,  form  a  group  which  has  a  series  of 
characters  in  common  that  distinguishes  them  from  all  other 
trees  and  plants.  Such  a  group  of  species  is  called  a  genus. 

Families  OF  Orders,  in  botanical  language,  are  groups 
of  genera  that  agree  in  certain  particulars.  Thus  the  sev 
eral  plants  well-known  as  mallows,  hollyhock,  okra,  and 
cotton,  are  representatives  of  as  many  different  genera. 
They  all  agree  in  a  number  of  points,  especially  as  regards 
the  structure  of  their  fruit.  They  are  accordingly  group 
ed  together  into  a  natural  family  or  order,  which  differs 
from  all  others. 

Classes,  Series,  and  Classification, —  Classes  are  groups 

*  For  a  masterly  statement  of  the  facts  and  evidence  honrinu:  on  these  points, 
wliirli  arc  of  the  <j«v;ilc'st  importance  to  the  ;i^rieiilturist,  see  Darwin's  works 
"On  the  OriLMn  of  Species/'  and  "On  the  Variation  of  Animals  and  Plant* 
»mler  Domestication." 


REPRODUCTIVE    ORGANS    OP   PLANTS.  299 

ol  orders,  and  Series  are  groups  of  classes.  In  botanical 
classification  as  now  universally  employed — classification 
after  the  Natural  System — all  plants  are  separated  into 
two  series,  as  follows : 

1.  Flowering  Plants    (Phwnogams)    which    produce 
flowers  and  seeds  with  embryos,  and 

2.  Flowerless  Plants  (Cryptogams)  that  have  no  proper 
flowers,  and  are  reproduced  by  spores  which  are  in  most 
cases  single  cells.     This  series  includes  Ferns,  Horse-tails, 
Mosses,  Liverworts,  Lichens,  Sea- weeds,  Mushrooms,  and 
Molds. 

The  use  of  classification  is  to  give  precision  to  our  no 
tions  and  distinctions,  and  to  facilitate  the  using  and  ac 
quisition  of  knowledge.  Series,  classes,  orders,  genera, 
species,  and  varieties,  are  as  valuable  to  the  naturalist  as 
pigeon  holes  are  to  the  accountant,  or  shelves  and  draw 
ers  to  the  merchant. 

Botanical  Nomenclature, — So,  too,  the  Latin  or  Greek 
names  which  botanists  employ  are  essential  for  the  discrim 
ination  of  plants,  being  equally  received  in  all  countries, 
and  belonging  to  all  languages  where  science  has  a  home. 
They  are  made  necessary  not  only  by  the  confusion  of 
tongues,  but  by  confusions  in  each  vernacular. 

Botanical  usage  requires  for  each  plant  two  names,  one 
to  specify  the  genus,  another  to  indicate  the  species. 
Thus  all  oaks  are  designated  by  the  Latin  word  Quercus, 
while  the  red  oak  is  Quercus  rubra,  the  white  oak  is 
Quercus  alba,  the  live  oak  is  Quercus  virens;  etc. 

The  designation  of  certain  important  families  of  plants 
is  derived  from  a  peculiarity  in  the  form  or  arrangement 
of  the  flower.  Thus  the  pulse  family,  comprising  the 
bean,  pea,  and  vetch,  as  well  as  lucern  and  clover,  are 
called  Papilionaceous  plants,  from  the  resemblance  of 
their  flowers  to  a  butterfly,  (Latin,  papilio).  Again,  tho 
mustard  family,  including  the  radish,  turnip,  cabbage,  wa- 


800  HOW   CROPS   GROW. 

ter-cress,  etc.,  are  termed  Cruciferous  plants,  because  their 
flowers  ha\e  four  petals  arranged  like  the  four  arms  of  a 
cross,  (Latin,  crux). 

The  flowers  of  a  large  natural  order  of  plants  are  ar 
ranged  side  by  side,  often  in  great  numbers,  on  the  expand 
ed  extremity  of  the  flower-stem.  Examples  are  the  thistle, 
dandelion,  sun-flower,  artichoke,  China-aster,  etc.,  which, 
from  bearing  such  compound  heads,  are  called  Composite 
plants. 

The  Coniferous  (cone-bearing)  plants  comprise  the 
pines,  larches,  hemlocks,  etc.,  whose  flowers  are  arranged 
in  conical  receptacles. 

The  flowers  of  the  carrot,  parsnip,  and  caraway,  are  ar 
ranged  at  the  extremities  of  stalks  which  radiate  from  a 
central  stem  like  the  arms  of  an  umbrella ;  hence  they  are 
called  Umbelliferous  plants,  (from  umbely  Latin,  for  little 
screen). 

§  a 

THE   FRUIT 

THE  FRUIT  comprises  the  seed-vessel  and  the  seed,  to 
gether  with  their  various  appendages. 

THE  SEED-VESSEL,  consisting  of  the  base  of  the  pistil  in 
its  matured  state,  exhibits  a  great  variety  of  forms  and 
characters,  which  serve,  chiefly,  to  define  the  different 
kinds  of  Fruits.  Of  these  we  shall  only  adduce  such  as 
are  of  common  occurrence  and  belong  to  the  farm. 

The  Nut  has  a  hard,  leathery  or  bony  shell,  that  does 
not  open  spontaneously.  Examples  are  the  acorn,  chest 
nut,  beech-nut,  and  hazel-nut.  The  ( up  of  the  acorn  and 
the  bur  of  the  others  is  a  sort  of  fleshy  calyx. 

The  Stone-fruit  or  Drupe  is  a  nut  enveloped  by  a 
fleshy  or  leathery  coating,  like  the  peach,  cherry,  and  plum, 


REPRODUCTIVE    ORGANS    OF    PLANTS.  301 

also  the  butternut  and  hickory-nut.  Raspberries  and 
blackberries  are  clusters  of  small  drupes. 

Pome  is  a  term  applied  to  fruits  like  the  apple  and 
pear,  the  core  of  which  is  the  true  seed-vessel,  originally 
belonging  to  the  pistil,  while  the  often  edible  flesh  is  the 
enormously  enlarged  and  thickened  calyx,  whose  withered 
tips  are  always  to  be  found  at  the  end  opposite  the  stem. 

The  Berry  is  a  many-seeded  fruit  of  which  the  entire 
seed-vessel  becomes  thick  and  soft,  as  the  grape,  currant, 
tomato,  and  huckleberry. 

Gonrd  fruits  have  externally  a  hard  rind,  but  are  fleshy 
in  the  interior.  The  melon,  squash,  and  cucumber,  are  of 
this  kind. 

The  Akene  is  a  fruit  containing  a  single  seed  which  does 
not  separate  from  its  dry  envelope.  The  so-called  seeds 
of  the  composite  plants,  for  example  the  sun-flower,  thistle, 
and  dandelion,  are  akenes.  On  removing  the  outer  husk 
or  seed-vessel  we  find  within  the  true  seed.  Many  akenes 
are  furnished  with  a  pappus,  a  downy  or  hairy  appendagey 
as  seen  in  the  thistle,  which  enables  the  seed  to  float  and 
be  carried  about  in  the  wind.  The  fruit  or  grain  of  buck 
wheat  is  akene-like. 

The  Grains  are  properly  fruits.  Wheat  and  maize  con 
sist  of  the  seed  and  the  seed-vessel  closely  united.  When 
these  grains  are  ground,  the  bran  that  comes  off  is  the 
seed-vessel  together  with  the  outer  coatings  of  the  seed. 
Barley-grain,  in  addition  to  the  seed-vessel,  has  the  petals 
of  the  flower  or  inner  chaff,  and  oats  have,  besides  these, 
the  calyx  or  outer  chaff  adhering  to  the  seed. 

Pod  is  the  name  properly  applied  to  any  dry  seed-ves 
sel  which  opens  and  scatters  its  seeds  when  ripe.  Several 
kinds  have  received  special  designations ;  of  these  we  need 
only  notice  one. 

The  Legume  is  a  pod,  like  that  of  the  bean,  which 
splits  into  two  halves,  along  whose  inner  edges  seeds  are 


302  now  CROPS  GROW. 

borne.  The  pulse  family,  or  papilionaceous  plants,  are  also 
termed  leguminous  from  the  form  of  their  fruit. 

THE  SEED,  or  ripened  ovule,  is  borne  on  a  stalk  which 
connects  it  with  the  seed-vessel.  Through  this  stalk  it  is 
supplied  with  nutriment  while  growing.  When  matured 
and  detached,  a  scar  commonly  indicates  the  point  of 
former  connection. 

The  seed  has  usually  two  distinct  coats  or  integuments. 
The  outer  one  is  often  hard,  and  is  generally  smooth.  In 
the  case  of  cotton-seed  it  is  covered  with  the  valuable  cot 
ton  fiber.  The  second  coat  is  commonly  thin  and  delicate. 

The  Kernel  lies  within  the  integuments.  In  many  cases 
it  consists  exclusively  of  the  embryo,  or  rudimentary 
plant.  In  others  it  contains,  besides  the  embryo,  what  has 
received  the  name  of  endosperm. 

The  Endosperm  forms  the  chief  bulk  of  all  the  grains.  If 
we  cut  a  seed  of  maize  in  two  lengthwise,  we  observe  ex 
tending  from  the  point  where  it  was  attached  to  the  cob 
the  soft  "  chit,"  #,  fig.  63,  which  is  the  embryo,  to  be  pres 
ently  noticed.  The  remainder  of  the  kernel,  a,  is  endo 
sperm;  the  latter,  therefore,  yields  in  great  part  the 
flour  or  meal  which  is  so  important  a  part  of  the  food  of 
man  and  animals. 

The  endosperm  is  intended  for  the  support  of  the  young 
pin nt  as  it  developes  from  the  embryo,  before  it  is  capable 
of  depending  on  the  soil  and  atmosphere  for  sustenance. 
It  is  not,  however,  an  indispensable  part  of  the  seed,  and 
may  be  entirely  removed  from  it,  without  thereby  prevent 
ing  the  growth  of  a  new  plant. 

The  Embryo  or  Germ  is  the  essential  and  most  import 
ant  portion  of  the  seed.  It  is,  in  fact,  a  ready-formed 
plant  in  miniature,  and  has  its  root,  stem,  leaves,  and  a 
bud.  although  these  organs  are  often  as  undeveloped  in 
form  us  they  arc  in  >i/,«-. 

As  above  mentioned,  the  chit  of  the  seeds  of  maize  and 


REPRODUCTIVE    ORGANS    OF    PLANTS.  33 

the  other  grains  is  the  embryo.  Its  form  is  with  difficulty 
distinguishable  in  the  dry  seeds,  but  when  they  have  been 
soaked  for  several  days  in  water,  it  is  readily  removed 
from  the  accompanying  endosperm,  and  plainly  exhibits 
its  three  parts,  viz.,  the  radicle,  the  plumule,  and  the 
cotyledon. 

In  fig.  63  is  represented  the  embryo  of  maize.     In  A 
and  It  it  is  seen  in  section  imbedded  in  the  endosperm. 
C  exhibits  the  detached  embryo.     The  Radicle,  r,  is  the 
rootlet  of  the  seed-plant,  or  rather  the  point  from  which 
downward  growth  proceeds,  from  which  the  first  true  roots 
are  produced.     The  Plumule,  c,  is  the  ascending  axis  of 
the  plant,  the  central  bud,  out  of  which  the  stem  with  new 
leaves,  flowers,  etc.,  is  developed.     The    Cotyledon,  b,  is 
in  structure  a  ready-formed  leaf,  which  clasps  the  plumule 
in    the   embryo,   as   the 
proper  leaves  clasp  the 
stem     in      the     mature 
maize-plant.     The  coty 
ledon  of  maize  does  not, 
however,    perform    the 
functions  of  a  leaf;    on 

the  contrary,  it  remains  in  the  soil  during  the  act  of  sprout 
ing,  and  its  contents,  like  those  of  the  endosperm,  are 
absorbed  by  the  plumule  and  radicle.  The  leaves  which 
appear  above-ground,  in  the  case  of  maize  and  the  other 
grains  (buckwheat  excepted,)  are  those  which  in  the 
embryo  were  wrapped  together  in  the  plumule,  where  they 
can  be  plainly  distinguished  by  the  aid  of  a  magnifier. 

It  will  be  noticed  that  the  true  grains  (which  have 
sheathing  leaves  and  hollow  jointed  stems)  are  monocot- 
yledonous  (one-cotyledoned)  in  the  seed.  As  has  been 
mentioned,  this  is  characteristic  of  plants  with  Endogenous 
or  inside-growing  stems,  (p.  268.) 

The  seeds  of  the  Exoyens  (outside-growers)  (p.  273)  are 
dicotyledonous,  i.  e.,  have  two  cotyledons.  Those  of 


304  HOW    CROPS    GROW. 

buckwheat,  flax,  and  tobacco,  contain  an  endosperm.  The 
seeds  of  nearly  all  other  exogenous  agricultural  plants  are 
destitute  of  an  endosperm,  and,  exclusive  of  the  coats, 
consist  entirely  of  embryo.  Such  are  the  seeds  of  the  Le- 
guminosa3,  viz.,  the  bean,  pea,  and  clover;  of  the  Crucif- 
era3,  viz.,  turnip,  radish,  and  cabbage ;  of  ordinary  fruits, 
the  apple,  pear,  cherry,  plum,  and  peach  ;  of  the  gourd 
family,  viz.,  the  pumpkin,  melon  and  cucumber ;  and  finally 
of  many  hard-wooded  trees,  viz.,  the  oak,  maple,  elm, 
birch,  and  beech. 

We  may  best  observe  the  structure  of  the  two-cotyle- 
doned  embryo  in  the  garden  or  kidney-bean.  After  a  bean 
has  been  soaked  in  warm  water  for  several  hours,  the  coats 
may  be  easily  removed,  and  the  two  fleshy  cotyledons,  c, 
c,  in  fi<r.  64,  are  found  divided  from  each  other  save  at  the 

"  O  * 

point  where  the  radicle,  a,  is  seen  projecting  like  a  blunt 
spur.  On  carefully  breaking  away 
one  of  the  cotyledons,  we  get  a  side 
view  of  the  radicle,  a,  and  plumule,^, 
the  former  of  which  was  partially  and 
the  latter  entirely  imbedded  between 
the  cotyledons.  The  plumule  plainly 
exhibits  two  delicate  leaves,  on  which 

the  unaided  eye  may  note  the  veins.     These  leaves  are 

folded  together  along  their  mid-ribs,  and  may  be  opened 

and  spread  out  with  help  of  a  needle. 

When  the  kidney-bean  ( Phaseolus)  germinates,  the  cot 
yledons  are  carried  up  into  the  air,  where  they  become 
green  and  constitute  the  first  pair  of  leaves  of  the  new 
plant.  The  second  pair  are  the  tiny  leaves  of  the  plumule 
just  described,  between  which  is  the  bud,  whence  all  the 
subsequent  aerial  organs  develope  in  succession. 

In  the  horse-bean,  (fltba),  as  in  the  pea,  the  cotyledons 
never  assume  the  office  of  leaves,  but  remain  in  the  soil  and 
gradually  yield  a  large  share  of  their  contents  to  the 


REPRODUCTIVE    ORGANS    OF   PLANTS.  305 

growing  plant,  shriveling  and  shrinking  greatly  in  bulk, 
and  finally  falling  away  and  passing  into  decay. 

§3. 

VITALITY    OF    SEEDS    AND     THEIR    INFLUENCE    ON    THE 
PLANTS    THEY    PRODUCE. 

Duration  of  Vitality, — In  the  mature  seed  when  kept 
Irom  excess  of  moisture,  the  embryo  lies  dormant.  The 
duration  of  its  vitality  is  very  various.  The  seeds  of  the 
willow,  it  is  asserted,  will  not  grow  after  having  once  be 
come  dry,  but  must  be  sown  when  fresh  ;  they  lose  their 
germinative  power  in  two  weeks  after  ripening. 

With  regard  to  the  duration  of  the  vitality  of  the 
seeds  of  agricultural  plants  there  is  no  little  conflict  of 
opinion  among  those  who  have  experimented  with  them. 

The  leguminous  seeds  appear  to  remain  capable  of 
germination  during  long  periods.  Girardin  sprouted  beans 
that  were  over  a  century  old.  It  is  said  that  Grimstone 
with  great  pains  raised  peas  from  a  seed  taken  from  a 
sealed  vase  found  in  the  sarcophagus  of  an  Egyptian  mum 
my,  presented  to  the  British  Museum  by  Sir  G.  Wilkinson, 
and  estimated  to  be  near  3,000  years  old. 

The  seeds  of  wheat  usually  lose  their  power  of  growth 
after  having  been  kept  3-7  years.  Count  Sternberg  and 
others  are  said  to  have  succeeded  in  germinating  wheat 
taken  from  an  Egyptian  mummy,  but  only  after  soaking 
it  in  oil.  Sternberg  relates  that  this  ancient  wheat  mani 
fested  no  vitality  when  placed  in  the  soil  under  ordinary 
circumstances,  nor  even  when  submitted  to  the  action  of 
acids  or  other  substances  which  gardeners  sometimes  em 
ploy  to  promote  sprouting.  Vi-hnorin,  from  his  own  trials, 
doubts  altogether  the  authenticity  of  the  "  mummy  wheat." 

Dietrich,  (floff.  Jahr.,  1862-3,  p.  77,)  experimented 
with  seeds  of  wheat,  rye,  and  a  species  of  Bromus,  which 


306  HOW   CROPS    GKOW. 

were  185  years  old.  Nearly  every  means  reputed  to 
favor  germination  was  employed,  but  without  success. 
After  proper  exposure  to  moisture,  the  place  of  the  germ, 
was  usually  found  to  be  occupied  by  a  slimy,  putrefying 
liquid. 

The  fact  appears  to  be  that  the  circumstances  under 
which  the  seed  is  kept  greatly  influence  the  duration  of 
its  vitality.  If  seeds,  when  first  gathered,  be  thoroughly 
dried,  and  then  sealed  up  in  tight  vessels,  or  otherwise 
kept  out  of  contact  of  the  air,  there  is  no  reason  why 
their  vitality  should  not  endure  for  ages.  Oxygen  and 
moisture,  not  to  mention  insects,  are  the  agencies  that 
usually  put  a  speedy  limit  to  the  duration  of  the  germiua- 
tive  power  of  seeds. 

In  agriculture  it  is  a  general  rule  that  the  newer  the 
seed  the  better  the  results  of  its  use.  Experiments  have 
proved  that  the  older  the  seed  the  more  numerous  the 
failures  to  germinate,  and  the  weaker  the  plants  it  pro 
duces. 

Londet  made  trials  in  1856-7  with  seed- wheat  of  the 
years  1856,  '55,  '54,  and  '53. 

The  following  table  exhibits  the  results,  which  illustrate 
the  statement  just  made. 

Per  cent  of  seeds     Length  of  leaves  four  days 
sprouted.  after  coming  up. 


Seed  of  1&53,  none  

"    "    1854,  51  0.4  to  0.8  inches  269 

"    "    1855,  73  1.2      "  365 

"    "    ia56,  74  1.6      "  404 

The  results  of  similar  experiments  made  by  Haberlandt 
on  various  grains,  are  contained  in  the  following  table: 

Per  cent  of  seeds  that  germinated  in  1861  from  tlie  years 


1850 

'51 

'54 

'55 

'57 

'58 

'59 

'60 

Wheat, 

0 

0 

8 

4 

73 

60 

84 

96 

By«, 

0 

0 

0 

0 

0 

0 

48 

100 

Barley, 

0 

0 

34 

0 

48 

33 

9:3 

89 

Outs, 

00 

0 

56 

48 

7:3 

32 

80 

96 

Maize, 

9 

not  tried. 

70 

56 

not  tried. 

77 

100 

97 

1CEPKODUCTIVE    ORGANS    OF   PLAINTS. 


». 


Results  of  the  Use  of  long-kept  Seeds,— The  met  that  old 
seeds  yield  weak  plants  is  taken  advantage  of  byw\C  florist 
in  producing  new  varieties.  It  is  said  that  while\the  one- 
year-old  seeds  of  Ten-weeks  Stocks  yield  single  flowers, 
those  which  have  been  kept  four  years  give  mostly  doublo 
flowers. 

In  case  of  melons,  the  experience  of  gardeners  goes  to 
show  that  seeds  which  have  been  kept  several,  even  seven 
years,  though  less  certain  to  come  up,  yield  plants  that 
.give  the  greatest  returns  of  fruit ;  while  plantings  of  new 
seeds  run  excessively  to  vines. 

Unripe  Seeds, — Experiments  by  Lucanus  prove  that 
seeds  gathered  while  still  unripe, — when  the  kernel  is  soft 
and  milky,  or,  in  case  of  cereals,  even  before  starch  has 
formed,  and  when  the  juice  of  the  kernel  is  like  water  in 
appearance, — are  nevertheless  capable  of  germination,  espe 
cially  if  they  be  allowed  to  dry  in  connection  with  the  stem 
(after-ripening.)  Such  immature  seeds,  however,  have  less 
vigorous  germinative  power  than  those  which  are  allowed 
to  mature  perfectly ;  when  sown,  many  of  them  fail  to 
come  up,  and  those  which  do,  yield  comparatively  weak 
plants  at  first  and  in  poor  soil  give  a  poorer  harvest  than 
well-ripened  seed.  In  rich  soil,  however,  the  plants  which 
do  appear  from  unripe  seed,  may,  in  time,  become  as  vig 
orous  as  any.  (Lucanus,  Vs.  /St.,  IV,  p.  253.) 

According  to  Siegert,  the  sowing  of  unripe  peas  tends  to 
produce  earlier  varieties.  Liebig  says :  "  The  gardener  is 
aware  that  the  flat  and  shining  seeds  in  the  pod  of  the 
Stock  Gillyflower  will  give  tall  plants  with  single  flowers, 
while  the  shriveled  seeds  will  furnish  low  plants  with 
double  flowers  throughout." 

Dwarfed  or  Light  Seeds,— Dr.  Mailer,  as  well  as  Hel!- 
riegel,  found  that  light  grain  sprouts  quicker  but  yields 
weaker  plants,  and  is  not  so  sure  of  germinating  as  heavy 
grain. 


308  HOW   CROPS   GROW. 

Baron  Liebig  asserts  (Natural  Laws  of  Husbandry ^ 
Am.  Ed.,  1863,  p.  24)  that  "the  strength  and  number  of 
the  roots  and  leaves  formed  in  the  process  of  germination, 
are,  (as  regards  the  non-nitrogenous  constituents,)  in  di 
rect  proportion  to  the  amount  of  starch  in  the  seed." 
Further,  "poor  and  sickly  seeds  will  produce  stunted 
plants,  which  will  again  yield  seeds  bearing  in  a  great 
measure  the  same  character."  On  the  contrary,  he  states 
(on  page  61  of  the  same  book,  foot  note,)  that  "  Boussing- 
ault  has  observed  that  even  seeds  weighing  two  or  three 
milligrames,  (l-30th  or  l-20th  of  a  grain,)  sown  in  an  ab 
solutely  sterile  soil,  will  produce  plants  in  which  all  the 
organs  are  developed,  but  their  weight,  after  mouths,  does 
not  amount  to  much  more  than  that  of  the  original  seed. 
The  plants  are  reduced  in  all  dimensions ;  they  may,  how 
ever,  grow,  flower,  and  even  bear  seed,  which  only  requires 
a  fertile  soil  to  produce  again  a  plant  of  the  natural  size" 
These  seeds  must  be  diminutive,  yet  placed  in  a  fertile  soil 
they  give  a  plant  of  normal  dimensions.  We  must  thence 
conclude  that  the  amount  of  starch,  glut  oil,  etc.- — in  other 
words  the  weight  of  a  seed — is  not  altogether  an  index  of 
the  vigor  of  the  plant  that  may  spring  from  it. 

Schubert,  whose  observations  on  the  roots  of  agricul 
tural  plants  are  detailed  in  a  former  chapter  (p.  242,)  says, 
as  the  result  of  much  investigation — "  the  vigorous  devel 
opment  of  plants  depends  far  less  upon  the  size  and 
weight  of  the  seed  than  upon  the  depth  to  which  it  is  cov 
ered  with  earth,  and  upon  the  stores  of  nourishment  which 
it  finds  in  its  first  period  of  life." 

Value  of  seed  as  related  to  its  Density, — From  a  series 
of  experiments  made  at  the  Royal  Ag.  College  at  Ciren- 
cester,  in  1803-4,  Prof.  Church  concludes  that  the  value 
of  seed-wheat  stands  in  a  certain  connection  with  its  spe 
cific  gravity,  (Practice  with  Science,  p.  107,  London,  1865.) 
He  found : — 


REPRODUCTIVE    ORGANS    OF   PLANTS.  309 

1.  That  seed- wheat  of  the  greatest  density  produces 
the  densest  seed. 

2.  The  seed-wheat  of  the  greatest  density  yields  the 
greatest  amount  of  dressed  corn. 

3.  The  seed-wheat  of  medium  density  generally  gives 
the  largest  number  of  ears,  but  the  ears  are  poorer  than 
those  of  the  densest  seed. 

4.  The  seed-wheat  of  medium  density  generally  pro 
duces  the  largest  number  of  fruiting  plants. 

5.  The  seed-wheats  which  sink  in  water  but  float  in  a 
liquid  having  the  specific  gravity  1.247,  are  of  very  low 
value,  yielding,  on  an  average,  but  34.4  Ibs.  of  dressed 
grain  for  every  100  yielded  by  the  densest  seed. 

The  densest  grains  are  not,  according  to  Church,  always 
the  largest.  The  seeds  he  experimented  with  ranged  from 
sp.  gr.  1.354  to  1.401. 


DIVISION  in. 

LIFE     OF     THE     PLANT. 

CHAPTER    L 
GERMINATION. 

INTRODUCTORY. 

Having  traced  the  composition  of  vegetation  from  its 
ojtimate  elements  to  the  proximate  organic  compounds, 
and  studied  its  structure  in  the  simple  cell  as  well  as  in  tho 
most  highly  developed  plant,  and,  as  far  as  needful,  explain 
ed  the  characters  and  functions  of  its  various  organs,  we 
approach  the-  subject  of  VEGETABLE  LIFE  and  NUTRITION, 
and  are  ready  to  inquire  how  the  plant  increases  in  bulk  and 
weight  and  produces  starch,  sugar,  oil,  albuminoids,  etc., 
v.-hich  constitute  directly  or  indirectly  almost  the  entire 
food  of  animals. 

The  beginning  of  the  individual  plant  is  in  the  seed,  at 
the  moment  of  fertilization  by  the  action  of  a  pollen  tube 
on  the  contents  of  the  embryo-sack.  Each  embryo  whoso 
development  is  thus  ensured,  is  a  plant  in  miniature,  or 
rather  an  organism  that  is  capable,  under  proper  circum 
stances,  of  unfolding  into  a  plant. 
310 


GERMINATION.  311 

The  first  process  of  development,  wherein  the  young- 
plant  commences  to  manifest  its  separate  life,  and  in  which 
it  is  shaped  into  its  proper  and  peculiar  form,  is  called 
germination. 

The  GENERAL  PROCESS  and  CONDITIONS  of  GERMINATION 
are  familiar  to  all.  In  agriculture  and  ordinary  garden 
ing  we  bury  the  ripe  and  sound  seed  a  little  way  in  the 
soil,  and  in  a  few  days,  it  usually  sprouts,  provided  it  finds 
a  certain  degree  of  warmth  and  moisture. 

Let  us  attend  somewhat  in  detail  first  to  the  phenomena 
of  germination  and  afterward  to  the  requirements  of  the 
awakening  seed. 


THE    PHENOMENA    OF    GERMINATION. 

The  student  will  do  well  to  watch  with  care  the  various 
stages  of  the  act  of  germination,  as  exhibited  in  several 
species  of  plants.  For  this  purpose  a  dozen  or  more  seeds 
of  each  plant  are  sown,  the  smaller,  one-half,  the  larger,  one 
inch  deep,  in  a  box  of  earth  or  saw-dust,  kept  duly  warm 
and  moist,  and  one  or  two  of  each  kind  are  uncovered  and 
dissected  at  successive  intervals  of  12  hours  until  the 
process  is  complete.  In  this  way  it  is  easy  to  trace  all  the 
visible  changes  which  occur  as  the  embryo  is  quickened. 
The  seeds  of  the  kidney-bean,  pea,  of  maize,  buckwheat, 
and  barley,  may  be  employed. 

We  thus  observe  that  the  seed  first  absorbs  a  large 
amount  of  moisture,  in  consequence  of  which  it  swells  and 
becomes  more  soft.  TVe  see  the  germ  enlarging  beneath 
the  seed  coats,  shortly  the  integuments  burst  and  the  radi 
cle  appears,  afterward  the  plumule  becomes  manifest. 

In  all  agricultural  plants  the  radicle  buries  itself  in  the 
soil.  The  plumule  ascends  into  the  atmosphere  and  seeks 
exposure  to  the  direct  light  of  the  sun. 


HOW   CROPS    GROW. 

The  endosperm,  if  the  seed  have  one,  and  in  many  cases 
the  cotyledons  (so  with  the  horse-bean,  pea,  maize,  and 
barley),  remain  in  the  place  where  the  seed  was  deposited. 
In  other  cases  (kidney-bean,  buckwheat,  squash,  radish, 
etc.,)  the  cotyledons  ascend  and  become  the  first  pair  of 
leaves. 

The  ascending  plumule  shortly  unfolds  new  leaves,  and 
if  coming  from  the  seed  of  a  branched  plant,  lateral  buds 
make  their  appearance.  The  radicle  divides  and  subdi 
vides  in  beginning  the  issue  of  true  roots. 

When  the  plantlet  ceases  to  derive  nourishment  from 
the  mother  seed,  the  process  is  finished. 


§3. 

THE    CONDITIONS    OF    GERMINATION. 

As  to  the  Conditions  of  Germination  we  have  to  con 
sider  in  detail  the  following : — 

a.  Temperature. — A  certain  range  of  warmth  is  essen 
tial  to  the  sprouting  of  a  seed. — Goppert,  who  experiment 
ed  with  numerous  seeds,  observed  none  to  germinate  be 
low  39°. 

Sachs  has  ascertained  for  various  agricultural  seeds  the 
extreme  limits  of  warmth  at  which  germination  is  possi 
ble.  The  lowest  temperatures  range  from  41°  to  55°,  the 
highest,  from  102°  to  110°.  Below  the  minimum  temper 
ature  a  seed  preserves  its  vitality,  above  the  maximum  it 
is  killed.  He  finds,  likewise,  that  the  point  at  which  the 
most  rapid  germination  occurs  is  intermediate  between 
these  two  extremes,  and  lies  between  79°  and  93°.  Either 
elevation  or  reduction  of  temperature  from  these  degrees 
retards  the  act  of  sprouting. 

In  the  following  table  are  giren  the  special  tempera' 
tures  for  six  common  plants. 


GERMINATION.  318 


Lowest 

Highest 

Temperature  of  most 

Temperature. 

Temperature. 

rapid  Germination. 

Wheat, 

41°  F. 

101°  F 

84°  F. 

Barley, 

41. 

104. 

84. 

Pea, 

44.5 

102. 

84. 

Maize, 

48. 

115. 

93. 

Scarlet-bean, 

49. 

111. 

79. 

Squash, 

54. 

115. 

93. 

For  all  agricultural  plants  cultivated  in  N"ew  England, 
a  range  of  temperature  of  from  55°  to  90°  is  adapted  for 
healthy  and  speedy  germination. 

It  will  be  noticed  in  the  above  Table  that  the  seeds  of 
plants  introduced  into  northern  latitudes  from  tropical  re 
gions,  as  the  squash,  bean,  and  maize,  require  and  endure 
higher  temperatures  than  those  native  to  temperate  lati 
tudes,  like  wheat  and  barley.  The  extremes  given 
above  are  by  no  means  so  wide  as  would  be  found  were 
we  to  experiment  with  other  plants.  It  is  probable  that 
some  seeds  will  germinate  nearly  at  32°,  or  the  freezing 
point  of  water,  while  the  cocoa-nut  is  said  to  yield  seed 
lings  with  greatest  certainty  when  the  heat  of  the  soil  is 
120°. 

Sachs  has  observed  that  the  temperature  at  which 
germination  takes  place  materially  influences  the  relative 
development  of  the  parts,  and  thus  the  form  of  the  seed 
ling.  According  to  this  industrious  experimenter,  very 
low  temperatures  retard  the  production  of  new  rootlets, 
buds,  and  leaves.  The  rootlets  which  are  rudimentary  in 
the  embryo  become,  however,  very  long.  On  the  other 
hand,  very  high  temperatures  cause  the  rapid  formation 
of  new  roots  and  leaves,  even  before  those  existing  in  the 
germ  are  fully  unfolded.  The  medium  and  most  favora 
ble  temperatures  bring  the  parts  of  the  embryo  first  into 
development,  at  the  same  time  the  rudiments  of  new  or 
gans  are  formed  which  are  afterward  to  unfold. 

b.  Moisture, — A  certain  amount  of  moisture  is  indis* 
pensable  to  all  growth.     In  germination  it  is  needful  that 
14 


314  now  CROPS  GROW. 

the  seed  should  absorb  water  so  that  motion  of  the  con- 
tents  of  the  germ-cells  can  take  place.  Until  the  seed  is 
more  or  less  imbued  with  moisture,  no  signs  of  sprouting 
are  manifested,  and  if  a  half-sprouted  seed  be  allowed  to 
dry  the  process  of  growth  is  effectually  checked. 

The  degree  of  moisture  different  seeds  will  endure  or 
require  is  exceedingly  various.  The  seeds  of  aquatic 
plants  naturally  germinate  when  immersed  in  water.  The 
seeds  of  many  land-plants,  indeed,  will  quicken  under  wa 
ter,  but  they  germinate  most  healthfully  when  moist  but 
not  wet.  Excess  of  water  often  causes  the  seed  to  rot. 

c.  Oxygen  Gas. — Free  Oxygen,  as  contained  in  the  air, 
is  likewise  essential.     Saussure  demonstrated  by  experi 
ment  that  proper  germination  is  impossible  in  its  absence, 
:nid  cannot  proceed  in  an  atmosphere  of  other  gases.     As 
we  shall  presently  see,  the  chemical  activity  of  oxygen 
appears  to  be  the  means  of  exciting  the  growth  of  the 
embryo. 

d.  Light. — It  has  been  taught  that  light  is  prejudicial 
to  germination,  and  that  therefore  seed  must  be  covered. 
(Johnston' *s  Lectures  on  Ag.  Chem.  &  Geology,  2d  JSng. 
Ed ,  pp.  226  &  227).     When,  however,  we  consider  that 
nature  does  not  bury  seeds  but  scatters  them  on  the  sur 
face  of  the  ground  of  forest  and  prairie,  where  they  are,  at 
the  most,  half-covered  and  by  no  means  removed  from  the 
light,  we  cannot  accept  such  a  doctrine.     The  warm  and 
moist  forests  of  tropical  regions,  which,  though   shaded, 
are  by  no  means  dark,  are  covered  with  sprouting  seeds. 
The  gardener  knows  that  the  seeds  of  heaths,  calceolarias, 
and  some  other  ornamental  plants,  germinate  best  when 
uncovered,  and  the  seeds  of  common  agricultural  plants 
will  sprout  when  placed  on  moist  sand  or  saw-dust,  with 
apparently  no  less  readiness  than  when  buried  out  of  sight. 

Finally,  R.    Hoffmann    (Jahresbericht  tiber  Agricultur 
Chem ,  1864,  p.  J 10)   has  found  in  experiments  with  24 


GERMINATION.  5U5 

kinds  of  agricultural  seeds  that  light  exercises  no  appieci- 
able  influence  of  any  kind  on  germination. 

The  Time  required  for  Germination  varies  exceedingly 
according  to  the  kind  of  seed.  As  ordinarily  observed, 
the  fresh  seeds  of  the  willow  begin  to  sprout  within  12 
hours  after  foiling  to  the  ground.  Those  of  clover,  wheat, 
and  other  grains,  germinate  in  three  to  five  days.  The 
fruits  of  the  walnut,  pine,  and  larch,  lie  four  to  six  weeks 
before  sprouting,  while  those  of  some  species  of  ash,  beech, 
and  maple,  are  said  not  to  germinate  before  the  expiration 
of  1^  or  2  years. 

The  starchy  and  thin-skinned  seeds  quicken  most  readi 
ly.  The  oily  seeds  are  in  general  more  slow,  while  such 
as  are  situated  within  thick  and  horny  envelopes  require 
the  longest  periods  to  excite  growth. 

The  time  necessary  for  germination  depends  naturally 
upon  the  favorableness  of  other  conditions.  Cold  and 
drought  delay  the  process,  when  they  do  not  check  it  al 
together.  Seeds  that  are  buried  deeply  in  the  soil  may  re 
main  for  years,  preserving,  but  not  manifesting,  their  vital 
ity,  because  they  are  either  too  dry,  too  cold,  or  have  not 
sufficient  access  to  oxygen  to  set  the  germ  in  motion. 

To  speak  with  precision,  we  should  distinguish  the  time 
from  planting  the  dry  seed  to  the  commencement  of  germ 
ination  which  is  marked  by  the  rootlet  becoming  visible, 
and  the  period  that  elapses  until  the  process  is  complete, 
i.  e.,  until  the  stores  of  the  mother-seed  are  exhausted, 
and  the  young  plant  is  wholly  cast  upon  its  own  resources. 

At  41°  F.  in  the  experiments  of  Haberlandt,  the  rootlet 
issued  after  4  days,  in  the  case  of  rye,  and  in  5-7  days  in 
that  of  the  otker  grains  and  clover.  The  sugar-beet,  how 
ever,  lay  at  this  temperature  22  days  before  beginning  to 
sprout. 

At  51°,  the  time  was  shortened  about  one-half  in  case 
of  the  seeds  just  mentioned.  Maize  required  11,  kidney 
boans  8,  and  tobacco  31  days  at  this  temperature. 


310  HOW    CROPS    GROW. 

At  65°  the  grains,  clover,  peas,  and  flax,  began  to  sprout 
in  one  to  two  days ;  rnaize,  beans,  and  sugar-beet,  in  3 
days,  and  tobacco  in  6  days. 

The  time  of  completion  varies  with  the  temperature 
much  more  than  that  of  beginning.  It  is,  for  example,  ac 
cording  to  Sachs, 

at  41-  55°  for  wheat  and  barley  4(M5  days,  • 

"  95-100°     "        "      "        "       10-12     " 

At  a  given  temperature  small  seeds  complete  germina 
tion  much  sooner  than  large  ones.  Thus  at  55-60°  the 
process  is  finished  with  beans  in  30-40  days. 

With  maize  in  30-35  days. 
"     wheat  "  20-25     " 
"     clover  "    8-10      " 

These  differences  are  simply  due  to  the  fact  that  the 
smaller  seeds  have  smaller  stores  of  nutriment  for  the 
young  plant,  and  are  therefore  more  quickly  exhausted. 

Proper  Depth  Of  Sowing. — The  soil  is  usually  the  me 
dium  of  moisture,  warmth,  etc.,  to  the  seed,  and  it  affects 
germination  only  as  it  influences  the  supply  of  these 
agencies ;  it  is  not  otherwise  essential  to  the  process.  The 
burying  of  seeds,  when  sown  in  the  field  or  garden,  serves 
to  cover  them  away  from  birds  and  keep  them  from  drying 
up.  In  the  forest,  at  spring-time,  we  may  see  innumerable 
seeds  sprouting  upon  the  surface,  or  but  half  covered  mih 
decayed  leaves. 

While  it  is  the  nearly  universal  result  of  experience  in 
temperate  regions  that  agricultural  seeds  germinate  most 
surely  when  sown  at  a  depth  not  exceeding  1-3  inches, 
there  are  circumstances  under  which  a  widely  different 
practice  is  admissible  or  even  essential.  In  the  light  and 
porous  soil  of  the  gardens  of  New  Haven,  peas  may  be 
sown  6  to  8  inches  deep  without  detriment,  and  are 
thereby  better  secured  from  the  ravages  of  the  domestic 
pigeon. 

The  Moqui    Indians,  dwelling    upon    the   table   lands 


GERMINATION.  31? 

of  the  higher  Colorado,  deposit  the  seeds  of  maize  12  or 
14  inches  below  the  surface.  Thus  sown,  the  plant 
thrives,  while,  if  treated  according  to  the  plan  usual  in  the 
United  States  and  Europe,  it  might  never  appear  above 
ground.  The  reasons  for  such  a  procedure  are  the  follow 
ing  :  The  country  is  without  rain  and  almost  without  dew, 
In  summer  the  sandy  soil  is  continuously  parched  by  the 
sun  at  a  temperature  often  exceeding  100°  in  the  shade. 
It  is  only  at  the  depth  of  a  foot  or  more  that  the  seed  finds 
the  moisture  needful  for  its  growth, — moisture  furnished 
by  the  melting  of  the  winter  snows.* 

R.  Hoffmann,  experimenting  in  a  light,  loamy  sand,  upon 
24  kinds  of  agricultural  and  market-garden  seeds,  found 
that  all  perished  when  buried  12  inches.  When  planted 
10  inches  deep,  peas,  vetches,  beans,  and  maize,  alone  came 
up;  at  8  inches  there  appeared,  besides  the  above,  wheat, 
millet,  oats,  barley,  and  colza ;  at  6  inches  those  already 
mentioned,  together  with  winter  colza,  buckwheat,  and 
sugar-beets ;  at  4  inches  of  depth  the  above,  and  mustard, 
red  and  white  clover,  flax,  horseradish,  hemp,  and  turnips ; 
finally,  at  3  inches,  lucern  also  appeared.  Hoffmann 
states  that  the  deep-planted  seeds  generally  sprouted  most 
quickly,  and  all  early  differences  in  development  disap 
peared  before  the  plants  blossomed. 

On  the  other  hand,  Grouven,  in  trials  with  sugar-beet 
seed,  made,  most  probably,  in  a  well-manured  and  rather 
heavy  soil,  found  that  sowing  at  a  depth  off  to  1^  inches, 
gave  the  earliest  and  strongest  plants ;  seeds  deposited  at 
a  depth  of  2|-  inches  required  5  days  longer  to  come  up 
than  those  planted  at  f  in.  It  was  further  shown  th.it 
seeds  sown  shallow  in  a  fine;  wet  clay  required  4-5  days 
longer  to  come  up  than  those  placed  at  the  same  depth 
in  the  ordinary  soil. 

Not  only  the  character  of  the  soil,  which  influences  the 

*  For  these  interesting  facts  the  writer  is  indebted  to  Prof.  J.  S.  Newberry. 


318  HOW   CROPS    GROW. 

supply  of  air,  and  warmth ;  but  the  kind  of  weather 
which  determines  both  temperature  and  degree  of  moist 
ure,  have  their  effect  upon  the  time  of  germination,  and 
since  these  conditions  are  so  variable,  the  rules  of  practice 
are  laid  down,  and  must  be  received  with,  a  certain  latitude. 


4. 


THE    CHEMICAL    PHYSIOLOGY    OF    GERMINATION. 

THE  NUTRITION  OF  THE  SEEDLING. — The  young  plant 
grows  at  first  exclusively  at  the  expense  of  the  seed.  It 
may  be  aptly  compared  to  the  suckling  animal,  which, 
when  new-born,  is  incapable  of  providing  its  own  nourish 
ment,  but  depends  upon  the  milk  of  its  mother. 

The  Nutrition  of  the  Seedling  falls  into  three  processes, 
which,  though  distinct  in  character,  proceed  simultaneous 
ly.  These  are,  1,  Solution  of  the  Nutritive  Matters  of 
the  Cotyledons  or  Endosperm  ;  2,  Transfer ;  and  3,  As 
similation  of  the  same. 

1*  The  Act  of  Solution  has  no  difficulty  in  case  of  dex- 1 
trin,  gum,  the  sugars,  albumin,  and  casein.  The  water  '• 
which  the  seed  imbibes  to  the  extent  of  one-fourth  to  [ 
five-fourths  of  its  weight,  at  once  dissolves  them. 

It  is  otherwise  with  the  fats  or  oils,  with  starch  and 
with  gluten,  which,  as  such,  are  nearly  or  altogether  insol 
uble  in  water.  In  the  act  of  germination  provision  is 
made  for  transforming  these  bodies  into  the  soluble  ones 

O 

above  mentioned.      So  far  as  these  changes  have  been 
traced,  they  are  as  follows : 

Solution  of  Jfiits. — Sachs  has  recently  found  that  squash- 
seeds,  which,  when  ripe,  contain  no  starch,  sugar,  or  dex 
trin,  but  are  very  rich  in  oil  (50°  |0,)  and  albumiuoidf 


GERMINATION.  319 

(40°  |0)  suffer  by  germination  such  chemical  change  that  the 
oil  rapidly  diminishes  in  quantity  (nine-tenths  disappears,) 
while  at  the  same  time  starch,  and,  in  some  case?,  sugar,  is 
formed.  ( Vs.  St.,  Ill,  p.  1.) 

Solution  of  Starch. — The  starch  that  is  thus  organized 
from  the  fat  of  the  oily  seeds,  or  that  which  exists  ready- 
formed  in  the  farinaceous  (floury)  seeds,  undergoes  further 
changes,  which  have  been  previously  alluded  to  (p.  78), 
whereby  it  is  converted  into  substances  that  are  soluble 
in  water,  viz.,  dextrin  and  grape  or  cane  sugar. 

Solution  of  Albuminoids. — Finally,  the  insoluble  al 
buminoids  are  gradually  transformed  into  soluble  modifi 
cations.  ; 

Chemistry  Of  Malt. — The  preparation  and  properties 
of  malt  may  serve  to  give  an  insight  into  the  nature  of 
the  chemical  metamorphoses  that  have  just  been  indicated. 

The  preparation  is  in  this  wise.  Barley  or  wheat 
(sometimes  rye)  is  soaked  in  water  until  the  kernels  are 
soft  to  the  fingers ;  then  it  is  drained  and  thrown  up  in 
heaps.  The  masses  of  soaked  grain  shortly  dry,  become 
heated,  and  in  a  few  days  the  embryos  send  forth  their 
radicles.  The  heaps  are  shoveled  over,  and  spread  out  so 
as  to  avoid  too  great  a  rise  of  temperature,  and  when  the 
sprouts  are  about  half  an  inch  in  length,  the  germination 
is  checked  by  drying.  The  dry  mass,  after  removing  the 
sprouts  (radicles,)  is  malt,  such  as  is  used  in  the  manufac 
ture  of  beer. 

Malt  thus  consists  of  starchy  seeds  whose  germination 
has  been  checked  while  in  its  early  stages.  The  only  prod 
uct  of  the  beginning  growth — the  sprouts — being  remov 
ed,  it  exhibits  in  the  residual  seed  the  first  results  of  the 
process  of  solution. 

The  following  figures,  derived  from  the  researches  of 
Stein,  in  Dresden,  ( Wildes  Centralblatt,  1860,  2,  pp.  8- 
23,)  exhibit  the  composition  of  100  parts  of  Barley,  and 


320  HOW   CHOPS   GROW. 

of  the  92  parts  of  Malt,  and  the  2J  of  Sprouts  which  100 
parts  of  barley  yield.* 


mptS.Qf}         (Wpts.Of]         (     2i/3  Of    J 

Composition  of  }•=•{  V-H  >4 

Barley.    \      [    Malt.    \      (  Sprouh.  } 

Ash  ..............................  2.42  2.11  0.29 

Starch  ...........................  54.48  47.43 

Fat  ..............................  3.56  2.09  0.08 

Insoluble  Albuminoids  ...........  11.02  9.02  0.37 

Soluble  "  ..........  1.26  1.96  0.40 

Dextrin  ........................  6.50  6.95  j 

Extractive  Matters  (soluble  in  wa-  0.47 

ter  and  destitute  of  nitrogen)..  0.90  3.68  ) 

Cellulose  .......................  19.86  18.76  0.89 

100  92  2.5 

It  is  seen  from  the  above  statement  that  starch,  fat,  and 
insoluble  albuminoids,  have  diminished  in  the  malting 
process;  while  soluble  albuminoids,  dextrin,  and  other 
soluble  non-nitrogenous  matters,  have  somewhat  increased 
in  quantity.  With  exception  of  3°|0  of  soluble  "extractive 
matters,"  f  the  diversities  in  composition  between  barley 
and  malt  are  not  striking. 

The  properties  of  the  two  are,  however,  remarkably  dif 
ferent.  If  malt  be  pulverized  and  stirred  in  warm  water 
(155°  F.)  for  an  hour  or  two,  the  whole  of  the  starch  dis 
appears,  while  sugar  and  dextrin  take  its  place.  The 
former  is  recognized  by  the  sweet  taste  of  the  wort,  as  tho 
solution  is  called.  On  heating  the  wort  to  boiling,  a 
quantity  of  albumin  is  coagulated,  and  may  be  separated 
by  filtering.  This  comes  in  part  from  the  transformation 
of  the  insoluble  albuminoids  of  the  barley.  On  adding 


*  The  analyses  refer  to  the^materials  in  the  dry  state.  Ordinarily  they  con 
tain  from  10  to  If!  jvr  cent  of  water.  It  must  not  he  omitted  to  mention  that  tho 
proportions  of  malt  .".ml  spronls.  as  well  as  their  composition,  vary  somewhat 
acc.onliiiLT  to  rirntmstarircs:  and  furthermore,  the  best  analyse?  which  it  is  pos 
Bible  to  make  are  but  approximate. 

t  The  term  extract/re  mutters  is  here  applied  to  soluble  substances,  whose 
precise  nature  is  not  understood.  They  constitute  i  mixture  which  the  cuemiai 
l«  not  able  to  analyze. 


GERMINATION.  321 

to  the  filtered  liquid  its  own  bulk  of  a.coLjl,  dextrin  be 
comes  evident,  being  precipitated  as  a  white  powder. 

Furthermore,  if  we  mix  2—3  parts  of  starch  with  one 
of  malt,  we  find  that  the  whole  undergoes  the  same  change. 
An  additional  quantity  of  starch  remains  unaltered.  ^ 
I  The  process  of  germination  thus  developes  in  the  seed 
an  agency  by  which  the  conversion  of  starch  into  soluble 
carbohydrates  is  accomplished  with  great  rapidity. 

Diastase. — Payen  &  Persoz  attribute  this  actioxute'a 
nitrogenous  substance  which  they  term  Diastase,^  and 
which  is  found  in  the  germinating  seed  in  the  vicinity  of 
the  embryo,  but  not  in  the  radicles.  They  assert  that  one 
part  of  diastase  is  capable  of  transforming  2,000  parts  of 
starch,  first  into  dextrin  and  finally  into  sugar,  and  that 
malt  yields  s^th  of  its  weight  of  this  substance. 

A  short  time  previous  to  the  investigations  of  Payen  & 
Persoz  (1833,)  Saussure  found  that  Mucidin*  the  soluble 
nitrogenous  body  which  may  be  extracted  from  gluten 
(p.  101,)  transforms  starch  in  the  manner  above  described, 
and  it  is  now  known  that  any  albuminoid  may  produce 
the  same  effect,  although  the  rapidity  of  the  action  and 
the  amount  of  effect  are  usually  far  less  than  that  exhibit 
ed  by  the  so-called  diastase. 

In  order,  however,  that  the  albuminoids  may  transform 
starch  as  above  described,  it  is  doubtless  necessary  that 
they  themselves  enter  into  a  state  of  alteration ;  they  are 
in  part  decomposed  and  disappear  in  the  process. 

These  bodies  thus  altered  become  ferments.  ' 

It  must  not  be  forgotten,  however,  that  in  all  cases  in 
which  the  conversion  of  starch  into  dextrin  and  sugar  is 
accomplished  artificially,  an  elevated  temperature  is  re 
quired,  whereas  in  the  natural  process,  as  shown  in  the 

*  SausBtire  designated  this  body  mucin,  but  this  terra  being  established  as  the 
name  of  the  characteristic  ingredient  of  animal  mucus,  Ritthausen  has  replaced 
It  by  mucidin. 

14* 


322 


HOW    CROPS    GROW. 


germinating  seed,  the  change  goes  on  at  ordinary  or  even 
low  temperatures. 

It  is  generally  taught  that  oxygen  acting  on  the  album 
inoids  in  presence  of  water  and  within  a  certain  range  of 
temperature  induces  the  decomposition  which  confers  on 
them  the  power  in  question. 

The  necessity  for  oxygen  in  the  act  of  germination  has 
been  thus  accounted  for,  as  needful  to  the  solution  of 
the  starch,  etc.,  of  the  cotyledons. 

This  may  be  true  at  first,  but,  as  we  shall  presently  see, 
the  chief  action  of  oxygen  is  probably  of  another  kind. 

How  diastase  or  other  similar  substances  accomplish  the 
change  in  question  is  not  certainly  known. 

Soluble  Starch, — The  conversion  of  starch  into  sugar 
and  dextrin  is  thus  in  a  sense  explained.  This  is  not,  how 
ever,  the  only  change  of 
which  starch  is  susceptible. 
In  the  bean,  (Phaseolus 
multiflorus],  Sachs  (Sitz- 
unysberichte  der  "Wiener 
Akad.,  XXXVII,  57)  in 
forms  us  that  the  starch  of 
the  cotyledons  is  dissolved, 
passes  into  the  seedling,  and 
reappears  (in  part,  at  least) 
as  starch,  without  conver 
sion  into  dextrin  or  sugar, 
as  these  substances  do  not 
appear  in  the  cotyledons  during  any  period  of  germina 
tion,  except  in  small  quantity  near  the  joining  of  the 
seedling.  Compare  p.  64,  Unorganized  Starch. 

The  same  authority  gives  the  following  account  of 
the  microscopic  changes  observed  in  the  starch-grains 
themselves,  as  they  undergo  solution.  The  starch-grains 
of  the  bean  hive  a  narrow  interior  cavity,  (as  seen  in 
fig.  G5,  1.)  This  at  first  becomes  filled  with  a  liquid. 


Fig.  65. 


n  E  RMINATION.  323 

Next,  the  cavity  appears  enlarged  (2,)  its  borders  assume 
a  corroded  appearance  (3,  4,)  and  frequently  channels  are 
seen  extending  to  the  surface  (4,  5,  6.)  Finally,  the 
cavity  becomes  so  large,  and  the  channels  so  extended, 
that  the  starch-grain  falls  to  pieces  (7,  8.)  Solution  con 
tinues  on  the  fragments  until  they  have  completely  disap 
peared.  In  this  process  it  is  most  probable  that  the  starch 
assumes  the  liquid  form  without  loss  of  its  proper  chemi 
cal  characters,  though  it  ceases  to  strike  a  blue  color  with 
iodine.* 

Soluble  Albuminoids.— As  we  have  seen  (p.  104,)  in 
soluble  animal  fibrin  and  casein,  by  long  keeping  with 
imperfect  access  of  air,  pass  into  soluble  bodies,  and  lat 
terly  E.  Mulder  has  shown  that  diastase  rapidly  accom 
plishes  the  same  change.  It  would  appear,  in  fact,  that 
the  conversion  of  a  small  quantity  of  any  albuminoid  into 
a  ferment,  by  oxidation,  is  sufficient  to  render  the  whole 
soluble.  The  ferment  exerts  on  the  bodies  from  which  it 
is  formed,  an  action  similar  to  that  manifested  by  it  to 
wards  starch  and  other  carbohydrates. 

The  production  of  small  quantities  of  acetic  and  lactic 
acids  (the  acids  of  vinegar  and  of  sour  milk)  has  been 
observed  in  germination.  These  acids  perhaps  assist  in 
the  solution  of  the  albuminoids. 

Gaseous  Products  of  Germination,  —  Before  leaving 
this  part  of  our  subject,  it  is  proper  to  notice  some  other 
results  of  germination  which  have  been  thought  to  belong 
to  the  process  of  solution.  On  referring  to  the  table  of 
the  composition  of  malt,  we  find  that  100  parts  of  dry 
barloy  yield  92  parts  of  malt  and  2|-  of  sprouts,  leaving 
5^-  parts  unaccounted  for.  In  the  malting  process  1|-  parts 
of  the  grain  are  dissolved  in  the  water  in  which  it  is 
soaked.  The  remaining  4  parts  escape  into  the  atmos 
phere  in  the  gaseous  form. 

*  According1  to  Liebig,  this  blue  reaction  depends  upon  the  adhesion  of  tho 
Iodine  to  the  starch,  and  is  not  the  result  of  a  chemical  combination. 


324  HOW   CROPS   GROW. 

Of  the  elements  that  assume  the  gaseous  condition,  ca*« 
bon  Joes  so  to  the  greatest  extent.  It  unites  with  atmos 
pheric  oxygen  (partly  with  the  oxygen  of  the  seed,  ac 
cording  to  Oudemans)  producing  carbonic  acid  gas  (COa.) 
Hydrogen  is  likewise  separated,  partly  in  union  with 
oxygen,  as  water  (H2O),  but  to  some  degree  in  the  free 
state.  Free  nitrogen  appears  in  considerable  amount, 
(Schulz,  Jour,  far  PmTct.  Chem.,  87,  p.  163,)  while  very 
minute  quantities  of  Hydrogen  and  of  Nitrogen  combine 
to  gaseous  ammonia  (NH3.) 

Heat  developed  in  Germination.  —  These  chemical 
changes,  like  all  processes  of  oxidation,  are  accompanied 
with  the  production  of  heat.  The  elevation  of  tempera 
ture  may  be  imperceptible  in  the  germination  of  a  single 
seed,  but  it  nevertheless  occurs,  and  is  doubtless  of  much 
importance  in  favoring  the  life  of  the  young  plant.  The 
heaps  of  sprouting  grain  seen  in  the  malt-house  warm  so 
rapidly  and  to  sucli  an  extent,  that  much  care  is  requisite 
to  regulate  the  process  ;  otherwise  the  malt  is  damaged  by 
over-heating. 

2.   The  Transfer  of  the  Nutriment  of  the  Seedling 

from  the  cotyledons  or  endosperm  where  it  has  undergone 
solution,  takes  place  through  the  medium  of  the  water 
which  the  seed  absorbs  so  largely  at  first.  This  water 
fills  the  cells  of  the  seed,  and,  dissolving  their  contents, 
carries  them  into  the  young  plant  as  rapidly  as  they  are 
required.  The  path  of  their  transfer  lies  through  the 
point  where  the  embryo  is  attached  to  the  cotyledons ; 
thence  they  are  distributed  at  first  chiefly  down  wards  into 
the  extending  radicles,  after  a  little  while  both  down 
wards  and  upwards  toward  the  extremities  of  the  seedling. 
Sachs  has  observed  that  the  carbohydrates  (sugar  and 
dextrin)  occupy  the  cellular  tissue  of  the  rind  and  pith, 
which  are  penetrated  by  numerous  air-passages ;  while  at 
first  the  albuminoids  chiefly  diffuse  themselves  through 


GERMINATION.  320 

the  intermediate  cambial  tissue,  which  is  destitute  of  air- 
passages,  and  are  present  in  largest  relative  quantity  at 
the  extreme  ends  of  the  rootlets  and  of  the  plumule. 

In  another  chapter  we  shall  notice  at  length  the  phenom 
ena  and  physical  laws  which  govern  the  diffusion  of  liq 
uids  into  each  other  and  through  membranes  similar  to 
those  which  constitute  the  walls  of  the  cells  of  plants, 
and  there  shall  be  able  to  gather  some  idea  of  the  causes 
which  set  up  and  maintain  the  transfer  of  the  materials 
of  the  seed  into  the  infant  plant. 

3,  Assimilation  is  the  conversion  of  the  transferred  nutri 
ment  into  the  substance  of  the  plant  itself.  This  process 
involves  two  stages,  the  first  being  a  chemical,  the  second, 
a  structural  transformation. 

The  chemical  changes  in  the  embryo  are,  in  part,  simply 
the  reverse  of  those  which  occur  in  the  cotyledon^ ;  viz., 
the  soluble  and  structureless  proximate  principles  are  met 
amorphosed  into  the  insoluble  and  organized  onos  of  the 
same  chemical  composition.  Thus,  dextrin  may  pass  into 
cellulose,  and  the  soluble  albuminoids  may  revert  in  part 
to  the  insoluble  condition  in  which  they  existed  in  the 
ripe  seed. 

But  many  other  and  more  intricate  changes  proceed  in 
in  the  act  of  assimilation.  With  regard  to  a  few  of  these 
we  have  some  imperfect  knowledge. 

Dr.  Sachs  informs  us  that  when  the  embryo  begins  to 
grow,  its  expansion  at  first  consists  in  the  enlargement  of 
the  ready-formed  cells.  As  a  part  elongates,  the  starch 
whiuh  it  contains  (or  which  is  formed  in  the  early  stages 
of  this  extension),  disappears,  and  sugar  is  found  in  its  stead, 
dissolved  in  the  juices  of  the  cells.  When  the  organ  has 
attained  its  full  size,  sugar  can  no  longer  be  detected ; 
while  the  walls  of  the  cells  are  found  to  have  grown  both 
in  circumference  and  thickness,  thus  indicating  the  accumu 
lation  of  cellulose. 


3'20  HOW   CROPS   GROW. 

Oxygen  Gas  needful  to  Assimilation. — Traube  has  made 
some  experiments,  which  seem  to  prove  conclusively  that 
the  process  of  assimilation  requires  free  oxygen  to  surround 
and  to  be  absorbed  by  the  growing  parts  of  the  germ. 
This  observer  found  that  newly-sprouted  pea-seedlings 
continued  to  dev elope  in  a  normal  manner  when  the  cot 
yledons,  radicles,  and  lower  part  of  the  stem,  were  with 
drawn  from  the  influence  of  oxygen  by  coating  with  var 
nish  or  oil.  On  the  other  hand,  when  the  tip  of  thf 
plumule,  for  the  length  of  about  an  inch,  was  coated  with 
oil  thickened  with  chalk,  or  when  by  any  means  this  part 
of  the  plant  was  withdrawn  from  contact  with  free  oxygen, 
the  seedling  ceased  to  grow,  withered,  and  shortly  perish 
ed.  Traube  observed  the  elongation  of  the  stem  by  the 
following  expedient. 

A  young  pea-plant  was  fastened  by  the  cotyledons  to  a 
rod,  and  the  stem  and  rod  were  both  graduated  by  deli 
cate  cross-lines,  laid  on  at  equal  intervals,  by  means  of  a 
brush  dipped  in  a  mixture  of  oil  and  indigo.  The  growth 
of  the  stem  was  now  manifest  by  the  widening  of  the 
spaces  between  the  lines;  and  by  comparison  with  those 
on  the  rod,  Traube  remarked  that  no  growth  took  place 
at  a  distance  of  more  than  10-12  lines  from  the  base,  of 
the  terminal  bud. 

Here,  then,  is  a  coincidence  which  appears  to  demonstrate 
that  free  oxygen  must  have  access  to  a  growing  part. 
The  fact  is  further  shown  by  varnishing  one  side  of  the 
stem  of  a  young  pea.  The  varnished  side  ceases  to  extend, 
the  uncoated  portion  continues  enlarging,  which  results  in, 
and  is  shown  by,  a  curvature  of  the  stem. 

Traube  further  indicates  in  what  manner  the  elabora 
tion  of  cellulose  from  sugar  may  require  the  cooperation 
of  oxygen  and  evolution  of  carbonic  acid,  as  expressed  by 
the  subjoined  equation. 

Glucose         Oxygen.  Carbonic  Add.     Water.  Cellulose. 

2  (0,a  Ha«  Oia)  4  m>  =  12  (CO,)  -    14  (HaO)  +  Cia  Hvo  O1§. 


FOOD    AFTER    GERMINATION.  3^7 

When  the  act  of  germination  is  finished,  which  occurs 
as  soon  as  the  cotyledons  and  endosperm  are  exhausted 
of  all  their  soluble  matters,  the  plant  begins  a  fully  inde 
pendent  life.  Previously,  however,  to  being  thus  thrown 
upon  its  own  resources,  it  has  developed  all  the  organs 
needful  to  collect  its  food  from  without ;  it  has  unfolded 
its  perfect  leaves  into  the  atmosphere,  and  pervaded  a  por 
tion  of  soil  with  its  rootlets. 

During  the  latter  stages  of  germination  it  gathers  its 
nutriment  both  from  the  parent  seed  and  from  the  exter 
nal  sources  which  afterward  serve  exclusively  for  its  sup 
port 

Being  fully  provided  with  the  apparatus  of  nutrition, 
its  development  suffers  no  check  from  the  exhaustion  of 
the  mother  seed,  unless  it  has  germinated  in  a  sterile  soil, 
or  under  other  conditions  adverse  to  vegetative  life. 


CHAPTER    IL 
§  I- 

THE  FOOD  OF  THE   PLANT  WHEN   INDEPENDENT  OF  THE 

SEED. 

This  subject  will  be  sketched  in  this  place  in  but  the 
briefest  outlines.  To  present  it  fully  would  necessitate 
entering  into  a  detailed  consideration  of  the  Atmosphere 
and  of  the  Soil  whose  relations  to  the  Plant,  those  of  the 
soil  especially,  are  very  numerous  and  complicated.  A 
separate  volume  is  therefore  required  for  the  adequate 
treatment  of  these  topics. 

The  R^p_ts_gjLa,  plant,  which  are  in  intimate  contact 
with  the  soil,  absorb  thence  the  water  that  fills  the  active 


328  HOW    CROPS   GKOW. 

cells ;  they  also  imbibe  such  salts  as  the  water  of  the  soil 
holds  in  solution ;  they  likewise  act  directly  on  the  soil, 
and  dissolve  substances,  which  are  thus  first  made  of  avail 
to  them.  The  compounds  that  the  plant  must  derive  from 
the  soil  are  those  which  are  found  in  its  ash,  since  these 
are  not  volatile,  and  cannot,  therefore,  exist  in  the  atmos 
phere.  The  root,  however,  commonly  takes  up  some  other 
elements  of  its  nutrition  to  which  it  has  immediate  access. 
Leaving  out  of  view,  for  the  present,  those  matters  which, 
though  found  in  the  plant,  appear  to  be  unessential  to  its 
growth,  viz.,  silica,  soda  and  manganese,  the  roots  absorb 
the  following  substances,  viz. : 

Sulphates  ~\  (     Potash. 

Phosphates  Lime. 

Nit  rates  and  Magnesia  and 

Chlorides  [     Iron. 

These  salts  enter  the  plant  by  the  absorbent  surfaces  of 
the  younger  rootlets,  and  pass  upwards  through  the  active 
portions  of  the  stem,  to  the  leaves  and  to  the  new-forming 
buds. 

The  Leaves,  which  are  unfolded  to  the  air,  gather  from 
it  CarboHTc  Acid  Gas.  This  compound  suffers  decompo 
sition  in  the  plant ;  its  Carbon  remains  there,  its  Oxygen 
or  an  equivalent  quantity,  very  nearly,  is  thrown  off  into 
ihe  air  again. 

The  decomposition  of  carbonic  acid  takes  place  only  by 
day  and  under  the  influence  of  the  sun's  light. 

From  the  carbon  thus  acquired  and  the  elements  of  wa- 
,er  with  the  cooperation  of  the  ash-ingredients,  the  plant 
organizes  the  Carbohydrates.  Probably  glucose,  perhaps 
dextrin  or  soluble  starch,  are  the  first  products  of  this 
synthesis. 

The  formation  of  carbohydrates  appears  to  proceed  in 
tie  <-hlorophyll-cells  of  the  leaf. 

The  Albuminoids  require  for  their  production  the  pres 
ence  of  a  compound  of  Nitrogen.  The  salts  of  Nitric 


FOOD    AFTER   GERMINATION. 

Acid  (nitrates)  are  commonly  the  chief,  am 
only  supply  of  this  element. 

The  other  proximate  principles,  viz.  pec»lK^|ihe  fats, 
the  alkaloids,  and  the  acids,  are  built  up  from  the  same 
food-elements.  In  all  cases  the  steps  in  the\apnstruc- 
tion  of  organic  matters  are  unknown  to  us,  or  subjects  of 
uncertain  conjecture. 

The  carbohydrates,  albuminoids,  etc.,  that  are  organized 
in  the  foliage,  are  not  only  transformed  into  the  solid  tis 
sues  of  the  leaf,  but  descend  and  diffuse  to  every  active 
organ  of  the  plant. 

The  plant  has  within  certain  limits  a  power  of  selecting 
its  food.  The  sea- weed,  as  has  been  remarked,  contains 
more  potash  than  soda,  although  the  latter  is  30  times 
more  abundant  than  the  former  in  the  water  of  the  ocean. 
Vegetation  cannot,  however,  entirely  shut  out  either  ex 
cess  of  nutritive  matters  or  bodies  that  are  of  no  use  or 
even  poisonous  to  it. 

The  functions  of  the  Atmosphere  are  essentially  the 
same  towards  plants,  whether  growing  under  the  condi 
tions  of  aqua3culture,  or  under  those  of  agriculture. 

The  Soil,  on  the  other  hand,  has  offic.es  which  arc  peculiar 
to  itself.  We  have  seen  that  the  roots  of  a  plant  have  the 
power  to  decompose  salts,  e.  g.  nitrate  of  potash  arid 
chloride  of  ammonium  (p.  170,)  in  order  to  appropriate 
one  of  their  ingredients,  the  other  being  rejected.  In 
aquaeculture,  the  experimenter  must  have  a  care  to  re 
move  the  substance  which  would  thus  accumulate  to  the 
detriment  of  the  plant.  In  agriculture,  the  soil,  by  virtue 
of  its  chemical  and  physical  qualities,  renders  such  reject 
ed  matters  comparatively  insoluble,  and  therefore  innoc 
uous. 

The  Atmosphere  is  nearly  invariable  in  its  composition 
at  all  times  and  over  all  parts  of  the  earth's  surface.  Its 
power  of  directly  feeding  crops  has,  therefore,  a  natural 
limit,  which  cannot  be  increased  by  art. 


330  HOW    CROPS    GROW. 

The  Soil,  on  the  other  hand,  is  very  variable  in  compo 
sition  and  quality,  and  may  be  enriched  and  improved,  or 
deteriorated  and  exhausted. 

From  the  Atmosphere  the  crop  can  derive  no  appreci 
able  quantity  of  those  elements  that  are  found  in  its  Ash. 

In  the  Soil,  however,  from  the  waste  of  both  plants  and 
animals,  may  accumulate  large  supplies  of  all  the  elements 
of  the  Volatile  part  of  Plants.  Carbon,  certainly  in  the 
form  of  carbonic  acid,  probably  or  possibly  in  the  condi 
tion  of  Humus  (Vegetable  Mould,  Muck),  may  thus  be 
put,  as  food,  at  the  disposition  of  the  plant.  Nitrogen  \t 
chiefly  furnished  to  crops  by  the  soil.  Nitrates  are  formed 
in  the  latter  from  various  sources,  and  ammonia-salts,  to 
gether  with  certain  proximate  animal  principles,  viz., 
urea,  guanin,  tyrosin,  uric  acid  and  hippuric  acid,  likewise 
serve  to  supply  nitrogen  to  vegetation  and  are  ingredients 
of  the  best  manures.  It  is,  too,  from  the  soil  that  the 
crop  gathers  all  the  Water  it  requires,  which  not  cnly 
serves  as  the  fluid  medium  of  its  chemical  and  structural 
metamorphoses,  but  likewise  must  be  regarded  as  the  ma 
terial  from  which  it  mostly  appropriates  the  Hydrogen 
and  Oxygen  of  its  solid  components. 


§2- 


THE    JUICES    OF    THE    PLANT,    THEIR    NATURE    AND 
MOVEMENTS. 

Very  erroneous  notions  are  entertained  with  regard  to 
the  nature  and  motion  of  sap.  It  is  commonly  taught  that 
there  are  two  regular  and  opposite  currents  of  sap  circu 
lating  in  the  plant.  It  is  stated  that  the  "  crude  sap  "  ia 
taken  up  from  the  soil  by  the  roots,  ascends  through  the 


MOTION    OF   THE    JUICES.  331 

vessels  (ducts)  of  the  wood,  to  the  leaves,  there  is  concen 
trated  by  evaporation,  "  elaborated "  by  the  processes 
that  go  on  in  the  foliage,  and  thence  descends  through  the 
vessels  of  the  inner  bark,  nourishing  these  tissues  in  its 
way  down.  The  facts  from  which  this  theory  of  the  sap 
first  arose,  all  admit  of  a  very  different  interpretation : 
while  numerous  considerations  demonstrate  the  essential 
falsity  of  the  theory  itself. 

Flow  of  sap  in  the  plant— not  constant  or  necessary. 
— We  speak  of  the  Flow  of  Sap  as  if  a  rapid  current 
were  incessantly  streaming  through  the  plant,  as  the  blood 
circulates  in  the  arteries  and  veins  of  an  animal.  This  is 
an  erroneous  conception. 

A  maple  in  early  March,  without  foliage,  with  its  whole 
stem  enveloped  in  a  nearly  impervious  bark,  its  buds 
wrapped  up  in  horny  scales,  and  its  roots  surrounded  by 
cold  or  frozen  soil,  cannot  be  supposed  to  have  its  sap  in 
motion.  Its  juices  must  be  nearly  or  absolutely  at  rest, 
and  when  sap  runs  copiously  from  an  orifice  made  in  the 
trunk,  it  is  simply  because  the  tissues  are  charged  with 
water  under  pressure,  which  escapes  at  any  outlet  that 
may  be  opened  for  it.  The  sap  is  at  rest  until  motion  is 
caused  by  a  perforation  of  the  bark  md  new  wood.  So, 
too,  when  a  plant  in  early  leaf  is  situated  in  an  atmosphere 
charged  with  moisture,  as  happens  on  a  rainy  day,  there  is 
little  motion  of  its  sap,  although,  if  wounded,  motion  will 
*)e  established,  and  water  will  stream  more  or  less  from  all 
parts  of  the  plant  towards  the  cut. 

Sap  does  move  in  the  plant  when  evaporation  of  water 
goes  on  from  the  surface  of  the  foliage.  This  always  hap 
pens  whenever  the  air  is  not  saturated  with  vapor.  When 
a  wet  cloth  hung  out,  dries  rapidly  by  giving  up  its 
moisture  to  the  air,  then  the  leaves  of  plants  lose  their 
water  more  or  less  readily,  according  to  the  nature  of 
ihe  foliage. 

Mr.  Lawes  found  that  in  the  moist  climate  of  England 


HOW   CROPS   GKO\v. 

common  plants  (Wheat,  Barley,  Beans,  Peas,  and  Clover) t 
exhaled  during  5  months  of  growth,  more  than  200  times 
their  (dry)  weight  of  water.  The  water  that  thus  evap 
orates  from  the  leaves  is  supplied  by  the  soil,  and  en 
tering  the  roots,  rapidly  streams  upwards  through  the 
stem  as  long  as  a  waste  is  to  be  supplied,  but  ceases  when 
evaporation  from  the  foliage  is  checked. 

The.  upward  motion  of  sap  is  therefore  to  a  great  de 
gree  independent  of  the  vital  processes,  and  comparatively 
unessential  to  the  welfare  of  the  plant. 

Flow  of  sap  from  the  plant.    "  Bleeding," — It  is  a 

familiar  fact,  that  from  a  maple  tree  "  tapped  "  in  spring 
time,  or  from  a  grape-vine  wounded  at  the  same  season,  a 
copious  flow  of  sap  takes  place,  which  continues  for  a  num 
ber  of  weeks.  The  escape  of  liquid  from  the  vine  is  com 
monly  termed  "  bleeding,"  and  while  this  rapid  issue  of 
sap  is  thus  strikingly  exhibited  in  comparatively  few 
cases,  bleeding  appears  to  be  a  universal  phenomenon,  one 
that  may  occur,  at  least,  to  some  degree,  under  certain  con 
ditions  with  every  plant. 

The  conditions  under  which  sap  flows  are  various,  ac 
cording  to  the  character  of  the  plant.  Our  perennial 
trees  have  their  annual  period  of  active  growtli  in  the 
warm  season,  and  their  vegetative  functions  are  nearly 
suppressed  during  cold  weather.  As  spring  approaches 
the  tree  renews  its  growth,  and  the  first  evidence  of  change 
witiiin  is  furnished  by  its  bleeding  when  an  opening  is 
made  through  the  bark  into  the  young  wood.  A  maple, 
tapped  for  making  sugar,  loses  nothing  until  the  spring 
warmth  attains  a  certain  intensity,  and  then  sap  begins  to 
flow  from  the  wounds  in  its  trunk.  The  flow  is  not  con 
stant,  but  fluctuates  with  the  thermometer,  being  more 
copious  when  the  weather  is  warm,  and  falling  off  or  suf 
fering  check  altogether  as  it  is  colder. 

The  stem  of  the  living  maple  is  always  charged   witli 


MOTION    OF   THE    JUICES.  333 

water,  and  never  more  so  than  in  winter.*  This  water  is 
either  pumped  into  the  plant,  so  to  speak,  by  the  root- 
power  already  noticed  (p.  248,)  or  it  is  generated  in  the 
trunk  itself.  The  water  contained  in  the  stem  in  cold 
weather  is  undoubtedly  that  raised  from  the  soil  in  the 
autumn.  That  which  first  flows  from  an  augur-hole,  in 
March,  may  be  simply  what  was  thus  stored  in  the  trunk ; 
but,  as  the  escape  of  sap  goes  on  for  14  to  20  days  at  the 
rate  of  several  gallons  per  day  from  a  single  tree,  new 
quantities  of  water  must  be  continually  supplied.  That 
these  are  pumped  in  from  the  root  is,  at  first  thought,  dif 
ficult  to  understand,  because  as  we  have  seen  (p.  250)  the 
root-power  is  suspended  by  a  certain  low  temperature 
(unknown  in  case  of  the  maple)  and  the  flow  of  sap  often 
begins  when  the  ground  is  covered  with  one  or  two  feet 
of  snow,  and  when  we  cannot  suppose  the  soil  to  have  a 
higher  temperature  than  it  had  during  the  previous  win 
ter  months.  Nevertheless,  it  must  be  that  the  deeper 
roots  are  warm  enough  to  be  active  all  the  winter  through, 
and  that  they  begin  their  action  as  soon  as  the  trunk  ac 
quires  a  temperature  'sufficiently  high  to  admit  the  move 
ment  of  water  in  it.  That  water  may  be  produced  in  the 
trunk  itself  to  a  slight  extent  is  by  no  means  impossible, 
for  chemical  changes  go  on  there  in  spring-time  with  much 
rapidity,  whereby  the  sugar  of  the  sap  is  formed.  These 
changes  have  not  been  sufficiently  investigated,  however, 
to  prove  or  disprove  the  generation  of  water,  and  we 
must,  in  any  case,  assume  that  it  is  the  root-power  which 
chiefly  maintains  a  pressure  of  liquid  in  the  tree. 

The  issue  of  sap  from  the  maple  tree  in  the  sugar-season 

*  Experiments  made  in  Tharand,  Saxony,  under  direction  of  Stoeckhardt 

show  that  the  proportion  of  water,  both  in  the  bark  and  wood  of  trees,  varies 

considerably  in  different  seasons  of  the  year,  ranging,  in  case  of  the  beech,  from 

35  to  49  per  cent  of  the  fresh-felled  tree.    The  greatest  proportion  of  water  iu 

;he  wood  was  found  in  the  months  of  December  and  January ;  in  the  bark,  in 

rarch  to  May.    The  minimum  of  water  in  the  wood  occurred  in  May,  June,  and 

v ;    in  the  bark,  much  irregularity  was  observed.     CJiem.  Ackersmanr,,  I860, 


334  HOW   CROPS   GROW. 

is  closely  connected  with  the  changes  of  temperature  that 
take  place  above  ground.  The  sap  begins  to  flow  from  a 
cut  when  the  trunk  itself  is  warmed  to  a  certain  point 
and,  in  general,  the  flow  appears  to  be  the  more  rapid  the 
warmer  the  trunk.  During  warm,  clear  days,  the  radiant 
heat  of  the  sun  is  absorbed  by  the  dark,  rough  surface  of 
the  tree  most  abundantly ;  then  the  temperature  of  the 
latter  rises  most  speedily  and  acquires  the  greatest  eleva 
tion — even  surpasses  that  of  the  atmosphere  by  several 
degrees ;  then,  too,  the  yield  of  sap  is  most  copious.  On 
clear  nights,  cooling  of  the  tree  takes  place  with  corre 
sponding  rapidity ;  then  the  snow  or  surface  of  the  ground 
is  frozen,  and  the  flow  of  sap  is  checked  altogether. 
From  trees  that  have  a  sunny  exposure,  sap  runs  earlier 
and  faster  than  from  those  having  a  cold  northern  aspect. 
Sap  starts  sooner  from  the  spiles  on  the  south  side  of  a 
tree  than  from  those  towards  the  north. 

Duchartre,  ( Comptes  Rendus,  IX,  754,)  passed  a  vine 
situated  in  a  grapery,  out  of  doors,  and  back  again, 
through  holes,  so  that  a  middle  portion  of  the  stem  was 
exposed  to  a  steady  winter  temperature  ranging  from  18 
to  10°  F.,  while  the  remainder  of  the  vine,  in  the  house, 
was  surrounded  by  an  atmosphere  of  70°  F.  Under 
these  circumstances  the  buds  within  developed  vigorously, 
but  those  without  remained  dormant  and  opened  not  a 
day  sooner  than  buds  upon  an  adjacent  vine  whose  stem 
was  all  out  of  doors.  That  sap  passed  through  the  cold 
part  of  the  stem  was  shown  by  the  fact  that  the  interior 
shoots  sometimes  wilted,  but  again  recovered  their  turgor, 
which  could  only  happen  from  the  partial  suppression  and 
renewal  of  a  supply  of  water  through  the  stem.  Pay  en 
examined  the  wood  of  the  vine  at  the  conclusion  of  the 
experiment,  and  found  the  starch  which  it  originally  con- 
i allied  to  have  been  equally  removed  from  the  warm  and 
the  exposed  p'trls. 

That  the  rate  at  which  sap  passed  through  the  stem  was 


MOTION    OF   THE    JUICES.  335 

influenced  by  its  temperature  is  a  plain  deduction  from 
the  fact  that  the  leaves  within  were  found  wilted  in  the 
morning,  while  they  recovered  toward  noon,  although  the 
temperature  of  the  air  without  remained  below  freezing. 
The  wilting  was  no  doubt  chiefly  due  to  the  diminished 
power  of  the  stem  to  transmit  water ;  the  return  of  the 
leaves  to  their  normal  condition  was  probably  the  conse 
quence  of  the  warming  of  the  stem  by  the  sun's  radiant 
heat.* 

One  mode  in  which  changes  of  temperature  in  the  trunk 
influence  the  flow  of  sap  is  very  obvious.  The  wood-cells 
contain,  not  only  water,  but  air.  Both  are  expanded  by 
heat,  and  both  contract  by  cold.  Air,  especially,  under 
goes  a  decided  change  of  bulk  in  this  way.  Water  ex 
pands  nearly  one-twentieth  in  being  warmed  from  32°  to 
212°,  and  air  increases  in  volume  more  than  one-third  by 
the  same  change  of  temperature.  When,  therefore,  the 
trunk  of  a  tree  is  warmed  by  the  sun's  heat  the  air  is  ex 
panded,  exerts  a  pressure  on  the  sap,  and  forces  it  out  of 
any  wound  made  through  the  bark  and  wood-cells.  It 
only  requires  a  rise  of  temperature  to  the  extent  of  a  few 
degrees  to  occasion  from  this  cause  alone  a  considerable 
flow  of  sap  from  a  large  tree.  (Hartig.) 

If  we  admit  that  water  continuously  enters  the  deep-ly 
ing  roots  whose  temperature  and  absorbent  power  must 
remain,  for  the  most  part,  invariable  from  day  to  day,  we 
should  have  a  constant  slow  escape  of  sap  from  the  trunk 
were  the  temperature  of  the  latter  uniform  and  sufficiently 
high.  This  really  happens  at  times  during  every  sugar- 
season.  When  the  trunk  is  cooled  down  to  the  freezing 
point,  or  near  it,  the  contraction  of  air  and  water  in  the 
tree  makes  a  vacuum  there,  sap  ceases  to  flow,  and  air  is 


*  The  temperature  of  the  air  is  not  always  a  sure  indication  of  that  of  the 
solid  bodies  which  it  surrounds.  A  thermometer  will  often  rise  by  exposure  of 
the  bulb  to  the  direct  rays  of  the  sun,  30  or  49°  above  its  indications  when  in  th« 
•bade. 


336  HOW   CROPS   GKOW. 

sucked  in  through  the  spile ;  as  the  trunk  becomes  heated 
again,  the  gaseous  and  liquid  contents  of  the  ducts  ex 
pand,  the  flow  of  sap  is  renewed,  and  proceeds  with  in 
creased  rapidity  until  the  internal  pressure  passes  its  max 
imum. 

As  the  season  advances  and  the  soil  becomes  heated,  the 
root-power  undoubtedly  acts  with  increased  vigor  and 
larger  quantities  of  water  are  forced  into  the  trunk,  but 
at  a  certain  time  the  escape  of  sap  from  a  wound  suddenly 
ceases.  At  this  period  a  new  phenomenon  supervenes. 
The  buds  which  were  formed  the  previous  summer  begin 
to  expand  as  the  vessels  are  distended  with  sap,  and  final 
ly,  when  the  temperature  attains  the  proper  range,  they 
unfold  into  leaves.  At  this  point  we  have  a  proper  mo 
tion  of  sap  in  the  tree,  whereas  before  there  was  little  mo 
tion  at  all  in  the  sound  trunk,  and  in  the  tapped  stem  the 
motion  was  towards  the  orifice  and  thence  out  of  the  tree. 

The  cessation  of  flow  from  a  cut  results  from  two  cir 
cumstances  :  first,  the  vigorous  cambial  growth,  whereby 
incisions  in  the  bark  and  wood  rapidly  heal  up;  and  sec 
ond,  the  extensive  evaporatioi  that  goes  on  from  foliage. 

That  evaporation  of  water  from  the  leaves  often  pro 
ceeds  more  rapidly  than  it  can  be  supplied  by  the  roots 
is  shown  by  the  facts  that  the  delicate  leaves  of  many 
plants  wilt  when  the  soil  about  their  roots  becomes  dry, 
that  water  is  often  rapidly  sucked  into  wounds  on  the 
stems  of  trees  which  are  covered  with  foliage,  and  that 
the  proportion  of  water  in  the  wood  of  the  trees  of  tem 
perate  latitudes  is  least  in  the  months  of  May,  Juno,  and 
July. 

Evergreens  do  not  bleed  in  the  spring-time.  The  oak 
loses  little  or  no  sap,  and  among  other  trees  great  diversity 
is  noticed  as  -to  the  amount  of  water  that  escapes  at  a 
wound  on  the  stem.  In  case  of  evergreens  we  have  a 
stem  destitute  of  all  proper  vascular  tissue,  and  admitting 
a  flow  of  liquid  only  through  the  perforations  of  the  wood- 


COMPOSITION    OF   THE   JUICE8.  837 

cells,  which,  from  their  content  of  resinous  matters, 
should  imbibe  water  less  readily  than  other  kinds  of  wood. 
Again,  the  leaves  admit  of  continual  evaporation,  and  fur 
nish  an  outlet  to  the  water  The  colored  heart-wood  ex 
isting  in  many  trees  is  impervious  to  water,  as  shown  by 
the  experiments  of  Boucherie  and  Hartig.  Sap  can  only 
flow  through  the  white,  so-called  sap-wood.  In  early  June, 
the  new  shoots  of  the  vine  do  not  bleed  when  cut,  nor 
does  sap  flow  from  the  wounds  made  by  breaking  them 
off  close  to  the  older  stem,  although  a  gash  in  the  latter 
bleeds  profusely.  In  the  young  branches,  there  are  no 
channels  that  permit  the  rapid  efflux  of  water. 

Composition  Of  Sap, — The  sap  in  all  cases  consists 
chiefly  of  water.  This  liquid,  as  it  is  absorbed,  brings  in 
from  the  soil  a  small  proportion  of  certain  saline  matters 
— the  phosphates,  sulphates,  nitrates,  etc.,  of  the  alkalies 
and  alkali-earths.  It  finds  in  the  plant  itself  its  organic 
ingredients.  These  may  be  derived  from  matters  stored 
in  reserve  during  a  previous  year,  as  in  the  spring  sap  of 
trees ;  or  may  be  newly  formed,  as  in  summer  growth. 

The  sugar  of  maple-sap,  in  spring,  is  undoubtedly  pro 
duced  by,  the  transformation  of  stnrch  which  is  found 
abundantly  in  the  wood  in  winter.  According  to  Hartig, 
(Jour,  far  Prakt.  Ch.,  5,  p.  217, 1835,)  all  deciduous  trees 
contain  starch  in  their  wood  and  yield  a  sweet  spring  sap, 
while  evergreens  contain  little  or  no  starch.  Hartig  re? 
ports  having  been  able  to  procure  from  the  root-wood  of 
the  horse-chestnut  in  one  instance  no  less  than  26  per  cent 
of  starch.  This  is  deposited  in  the  tissues  during  sum 
mer  and  autumn  to  be  dissolved  for  the  use  of  the  plant 
in  developing  new  foliage.  In  evergreens  and  annual 
plants  the  organic  matters  of  the  sap  are  derived  more  di 
rectly  from  the  foliage  itself.  The  leaves  absorb  carbonic 
acid  and  unite  its  carbon  to  the  elements  of  water,  with 
the  production  of  sugar  and  other  carbohydrates.  In  the 
leaves,  also,  probably  nitrogen  from  the  nitrates  and  am- 
15 


838  HOW    CROPS   GROW. 

monia-salts  gathered  by  the  roots,  is  united  to  carbon,  hy 
drogen,  and  oxygen,  in  the  formation  of  albuminoids. 

Besides  sugar,  malic  acid  and  minute  quantities  of  al 
bumin  exist  in  maple  sap.  Towards  the  close  of  the 
sugar-season  the  sap  appears  to  contain  other  organic  sub 
stances  which  render  the  sugar  impure,  brown  in  color, 
and  of  different  flavor. 

It  is  a  matter  of  observation  that  maple-sugar  is  whiter, 
purer,  and  "grains"  or  crystallizes  more  readily  in  those 
years  when  spring-rains  or  thaws  are  least  frequent.  This 
fact  would  appear  to  indicate  that  the  brown  organic 
matters  which  water  extracts  from  leaf-mould  may  enter 
the  roots  of  the  trees,  as  is  the  belief  of  practical  men. 

The  spring-sap  of  many  other  deciduous  trees  of  tem- 
]><M-ate  climates  contains  sugar,  but  while  it  is  cane  sugar 
in  the  maple,  in  other  trees  it  consists  mostly  or  entirely 
of  grape  sugar. 

Sugar  is  the  chief  organic  ingredient  in  the  juice  of  the 
sugar  cane,  Indian  corn,  beet,  carrot,  turnip,  and  parsnip. 

The  sap  that  flows  from  the  vine  and  from  many  culti 
vated  herbaceous  plants  contains  little  or  no  sugar;  in 
that  of  the  vine,  gum  or  dextrin  is  found  in  its  stead. 

What  has  already  been  stated  makes  evident  that  we 
cannot  infer  the  quantity  of  sap  in  a  plant  from  what  may 
run  out  of  an  incision,  for  the  sap  that  thus  issues  is  for 
the  most  part  water  forced  up  from  the  soil.  It  is  equally 
plain  that  the  sap,  thus  collected,  has  not  the  normal 
composition  of  the  juices  of  the  plant ;  it  must  be  diluted, 
and  must  be  the  more  diluted  the  longer  and  the  more  rap 
idly  it  flows. 

Ulbricht  has  made  partial  analyses  of  the  sap  obtained 
from  the  stumps  of  potato,  tobacco  and  sun-flower  plants. 
He  found  that  successive  portions,  collected  separately, 
exhibited  a  decreasing  concentration.  In  sunflower  sap, 
gathered  in  live  successive  portions,  the  liter  contained 
the  following  quantities  (grains)  of  solid  matter: 


COMPOSITION    OF   THE    JUICES.  339 

12345 

Volatile  substance      -     1.45     0.60    0.30    0.25    0/21 
Ash 1.58     1.56     1.18    0.70    0.60 


Total      -.-.    3.03    2.16     1.48    0.95     0.81 

The  water  which  streams  from  a  wound  dissolves  and 
carries  forward  with  it  matters,  that  in  the  uninjured  plant 
would  probably  suffer  a  much  less  rapid  and  extensive 
translocation.  From  the  stump  of  a  potato-stalk  would 
issue  by  the  mere  meciianical  effect  of  the  flow  of  water 
substances  generated  in  the  leaves  whose  proper  movement 
in  the  uninjured  plant  would  be  downwards  into  tho 
tubers. 

Different  kinds  Of  sap. — It  is  necessary  at  this  point 
in  our  discussion  to  give  prominence  to  the  fact  that  there 
are  different  kinds  of  sap  in  the  plant.  As  we  have  seen, 
(p.  267,)  the  cross  section  of  the  plant  presents  two  kinds 
of  tissue,  the  cellular  and  vascular.  These  carry  different 
juices,  as  is  shown  by  their  chemical  reactions.  In  the 
cell-tissues  exist  chiefly  the  non-nitrogenous  principles, 
sugar,  starch,  oil,  etc.  The  liquid  in  these  cells,  as  Sachs 
has  shown,  commonly  contains  also  organic  acids  and  acid- 
salts,  and  henoe  gives  aTWtte  color  to -reef  litmus.  In  the 
vascular  tissue  albuminoids  preponderate,  and  the  sap  of 
the  ducts  commonly  has  an  alkaline  reaction  towards  test 
papers.  These  Different  kinds  of  sap  are  not,  however, 
always  strictly  confined  to  eitiier  tissue.  In  the  root-tips 
and  buds  of  many  plants  (maize,  squash,  onion)  the  young 
(new-formed)  cell-tissue  is  alkaline  from  the  preponderance 
of  albuminoids,  while  the  spring  sap  flowing  from  the 
ducts  and  wood  of  the  maple  is  faintly  acid. 

In  many  plants  is  found  a  system  of  channels  (milk- 
ducts)  independent  of  the  vascular  bundles,  which  contain 
an  opaque,  white,  or  yellow  juice.  This  liquid  is  seen  to 


S40  HOW   CROPS   GROW. 

exude  from  the  broken  stem  of  the  milk-weed  (Asclepias^ 
of  lettuce,  or  of  celandine  (Chelidonium^)  and  may  be 
noticed  to  gather  in  drops  upon  a  fresh-cut  slice  of  the 
sweet  potato.  The  milky  juice  often  differs  not  more 
strikingly  in  appearance  than  it  does  in  ta?te,  from  the 
transparent  sap  of  the  cell-tissue  and  vascular  bundles. 
The  former  is  commonly  acrid  and  bitter,  while  the  latter 
is  sweet  or  simply  insipid  to  the  tongue. 

Motion  of  the  Nutrient  Matters  of  the  plant,— The 

occasional  rapid  passage  of  a  current  of  water  upwards 
through  the  plant  must  not  be  confounded  with  the  normal, 
necessary,  and  often  contrary  motion  of  the  nutrient  mat 
ters  out  of  which  new  growth  is  organized,  but  is  an  in 
dependent  or  highly  subordinate  process  by  which  the 
plant  adapts  itself  to  the  constant  changes  that  are  taking 
place  in  the  soil  and  atmosphere  as  regards  their  content 
of  moisture. 

A  plant  supplied  with  enough  moisture  to  keep  its  tis 
sues  turgid  is  in  a  normal  state,  no  matter  whether  the 
water  within  it  is  nearly  free  from  upward  flow  or  ascends 
rapidly  to  compensate  the  waste  by  evaporation.  In  both 
cases  the  motion  of  the  matters  dissolved  in  the  sap  is 
nearly  the  same.  In  both  cases  the  plant  developes  nearly 
alike.  In  both  cases  the  nutritive  matters  gathered  at  the 
root-tips  ascend,  and  those  gathered  by  the  leaves  descend, 
being  distributed  to  every  growing  cell ;  and  these  motions 
are  comparatively  independent  of,  and  but  little  influenced 
by,  the  motion  of  the  water  in  which  they  are  dissolved. 

The  upward  flow  of  sap  in  the  plant  is  confined  to  the 
vascular  bundles,  whether  these  are  arranged  symmetri 
cally  and  compactly,  as  in  exogenous  plants,  or  distributed 
singly  through  the  stem,  as  in  the  endogens.  This  is  not 
only  seen  upon  a  bleeding  stump,  but  is  made  evident  by 
the  oft-observed  fact  that  colored  liquids,  when  absorbed 
into  a  plant  or  cutting,  visibly  follow  the  course  of  the 


MOVEMENTS    OF   NUTRIENT   MATTERS.  341 

vessels,  though  they  do  not  commonly  penetrate  the  spira. 
ducts,  but  ascend  in  the  sieve-cells  of  the  cambium.* 

The  rapid  supply  of  water  to  the  foliage  of  a  ,plant, 
either  from  the  roots  or  from  a  vessel  in  which  the  cut 
stem  is  immersed,  goes  on  when  the  cellular  tissues  of  the 
bark  and  pith  are  removed  or  interrupted,  but  is  at  once 
checked  by  severing  the  vascular  bundles. 

The  proper  motion  of  the  nutritive  matters  in  the  plant 
— of  the  salts  dissolved  from  the  soil  and  of  the  organic 
principles  compounded  from  carbonic  acid,  water,  and 
nitric  acid  or  ammonia  in  the  leaves — is  one  of  slow  dif 
fusion  mostly  through  the  walls  of  imperforate  cells,  and 
goes  on  in  all  directions.  New  growth  is  the  formation 
and  expansion  of  new  cells  into  which  nutritive  substances 
are  imbibed,  but  not  poured  through  visible  passages. 
When  closed  cells  are  converted  into  ducts  or  visibly  com 
municate  with  each  other  by  pores,  their  expansion  has 
ceased.  Henceforth  they  merely  become  thickened  by  in 
terior  deposition. 

Movements  of  Nutrient  Matters  in  the  Bark  or  Rind, 
— The  ancient  observation  of  what  ordinarily  ensues  when 
a  ring  of  bark  is  removed  from  the  stem  of  an  exogenous 
tree,  led  to  the  erroneous  assumption  of  a  formal  down 
ward  current  of  "elaborated"  sap  in  the  bark.  When  a 
cutting  from  one  of  our  common  trees  is  girdled  at  it8 
middle  and  then  placed  in  circumstances  favorable  for 
growth,  as  in  moist,  warm  air,  with  its  lower  extremity  in 
water,  roots  form  chiefly  at  the  edge  of  the  bark  just 
above  the  removed  ring.  The  twisting,  or  half-breaking, 
as  well  as  ringing  of  a  layer,  promotes  the  development 
of  roots.  Latent  buds  are  often  called  forth  on  the  stems 
of  fruit  trees,  and  branches  grow  more  vigorously,  Toy 
making  a  transverse  incision  through  the  bark  just  below 

*  As  in  Unger's  experiment  of  placing  a  hycicinth  in  the  juice  of  the  poke- 
weed  (Phytolacca,)  or  in  Hallier's  observations  on  cuttings  dipped  in  cherry-juice, 
(FA  «.,  IX,  p.  1.) 


54-2 


HOW    CROPS    GROW. 


the  point  of  their  issue. 
Girdling  a  fruit  -  bearing 
branch  of  the  vino  near  its 
junction  with  the  older  wood 
has  the  effect  of  greatly  en 
larging  the  grapes.  It  is 
well  known  that  a  wide 
wound  made  on  the  stem  of  a 
tree  heals  up  by  the  formation 
of  new  wood,  and  commonly 
the  growth  is  most  rapid  and 
abundant  above  the  cut. 
From  these  facts  it  was  con 
cluded  that  sap  descends  in 
the  bark,  and,  not  being  able 
to  pass  below  a  wound,  leads 
to  the  organization  of  new 
roots  or  wood  just  above  it. 

The  accompanying  illustration, 
fig.  66,  represents  the  base  of  a  cut 
ting  from  an  exogenous  stem  (pear 
or  currant)  girdled  at  B  and  kept  for 
some  days  immersed  in  water  to  the 
depth  indicated  by  the  line  L.  The 
first  manifestation  of  growth  is  the 
formation  of  a  protuberance  at  the 
lower  edge  of  the  bark,  which  is 
known  to  gardeners  as  a  callous,  C. 
This  is  an  extension  of  the  cellular 
tis-ur.  From  the  callous  shortly 
appear  rootlets,  II,  which  originate 
from  the  vascular  1  issue.  Rootlets 
al-o  break  from  the  stem  above  the 
callous  and  also  above  the  water,  if 
the  air  be  moist.  They  appear  like 
wise,  though  in  less  number,  below 
the  girdled  place. 

Nearly  all  the  organic  sub 
stances  (carbohydrates,  al 
buminoids,  lignin,  etc.,)  that 


MOVEMENTS    OF    NUTRIENT    MATTERS.  343 

arc  formed  in  a  plant  are  produced  in  the  leaves, 
and  must  necessarily  find  their  way  down  to  nourish 
the  stem  and  roots.  The  facts  just  mentioned  demon 
strate,  indeed,  that  they  do  go  down  in  the  bark.  We 
have,  however,  no  proof  that  there  is  a  downward 
flow  of  sap.  Such  a  flow  is  not  indicated  by  a  single 
fact,  for,  as  we  have  before  seen,  the  only  current  of  water 
in  the  uninjured  plunt  is  the  upward  one  which  results 
from  root-action  and  evaporation,  and  that  is  variable  and 
mainly  independent  of  the  distribution  of  nutritive  matters. 
Closer  investigation  has  shown  that  the  most  abundant 
downward  movement  of  the  nutrient  matters  generated 
in  the  leaves  proceeds  in  the  thin-walled  sieve-cells  of  the 
cambium,  which,  in  exogens,  is  young  tissue  common  to 
the  outer  wood  and  the  inner  bark — which,  in  fact,  unites 
bark  and  wood.  The  tissues  of  the  leaves  communicate 
directly  with,  and  are  a  continuation  of,  the  cambium,  and 
hence  matters  formed  by  the  leaves  must  move  most  rapid 
ly  in  the  cambium.  If  they  pass  with  greatest  freedom 
through  the  sieve-cells,  the  fact  is  simply  demonstration 
that  the  latter  communicate  most  directly  with  those  parts 
of  the  leaf  in  which  the  matters  they  conduct  are  organized. 

In  endogenous  plants  and  in  some  exogens  (Piper  me 
dium,  Amaranthus  sanguineus]  the  vascular  bundles  con 
taining  sieve-cells  pass  into  the  pith  and  are  not  confined  to 
the  exterior  of  the  stem.  Girdling  such  plants  does  not  give 
the  result  above  described.  With  them,  roots  are  formed 
chiefly  or  entirely  at  the  base  of  the  cutting,  (Hanstein,) 
and  not  above  the  girdled  place. 

In  all  cases,  without  exception,  the  matters  organized  in 
the  leaves,  though  most  readily  and  abundantly  moving 
downwards  in  the  vascular  tissues,  are  not  confined  to 
them  exclusively.  When  a  ring  of  bark  is  removed  from 
a  tree,  the  new  cell-tissues,  as  well  as  the  vascular,  are  in 
terrupted.  Notwithstanding,  matters  are  transmitted 
downwards,  through  the  older  wood.  When  but  a  narrow 


344  HOW   CROPS   GROW. 

ring  of  bark  is  removed  from  a  cutting,  rocts  often  appear 
below  the  incision,  though  in  less  number,  and  .the  new 
growth  at  the  edges  of  a  wound  on  the  trunk  of  a  tree, 
though  most  copious  above,  is  still  decided  below — goes 
on,  in  fact,  all  around  the  gash. 

Both  the  cell-tissue  and  the  vascular  thus  admit  of  the 
transport  of  the  nutritive  matters  downwards.  In  the 
former,  the  carbohydrates — starch,  sugar,  inulin — the  fats, 
and  acids,  chiefly  occur  and  move.  In  the  large  ducts,  air  is 
contained,  except  when  by  vigorous  root-action  the  stem 
is  surcharged  with  water.  In  the  sieve-ducts  (cambium) 
are  found  the  albuminoids,  though  not  unmixed  with  car 
bohydrates.  If  a  tree  have  a  deep  gash  cut  into  its  stem, 
(but  not  reaching  to  the  colored  heart-wood,)  growth  is 
not  suppressed  on  either  side  of  the  cut,  but  the  nutritive 
matters  of  all  kinds  pass  out  of  a  vertical  direction 
around  the  incision,  to  nourish  the  new  wood  above  and 
below.  Girdling  a  tree  is  not  fatal,  if  done  in  the  spring 
or  early  summer  when  growth  is  rapid,  provided  that  the 
younsj  cells,  which  form  externally,  are  protected  from 
dryness  and  other  destructive  influences.  An  artificial 
bark,  i.  e.,  a  covering  of  cloth  or  clay  to  keep  the  exposed 
wood  moist  and  away  from  air,  saves  the  tree  until  the 
wound  heals  over.*  In  these  cases  it  is  obvious  that  the 
substances  which  commonly  preponderate  in  the  sieve- 
ducts  must  pass  through  the  cell-tissue  in  order  to  reach 
the  p^int  where  they  nourish  the  growing  organs. 

Evidence  that  nutrient  matters  also  pass  upwards  in 
the  bark  is  furnished,  not  only  by  tracing  the  course  of 
colored  liquids  in  the  stem,  but  also  by  the  fact  that  undo 
veloped  buds  perish  in  most  cases  when  the  stem  is  gir 
dled  between  them  and  active  leaves.  In  the  exceptions 
to  this  rule,  the  vascular  bundles  penetrate  the  pith,  and 

*  If  the  freehly  exposed  wood  he  rubbed  or  wiped  with  a  clolh,  whereby  tho 
aioist  'wmtlai  layer  (of  cells  containing  nuclei  aud  capable  of  IT  iltiplying)  is  re 
moved,  no  growth  can  occur.  Ratzeburg. 


MOVEMENTS    OF    XUTBIEXT   MATTERS.  345 

thereby  demonstrate  that  they  are  the  channels  of  this 
movement.  A  minority  of  these  exceptions  again  makes 
evident  that  the  sieve-cells  are  the  path  of  transfer,  for,  as 
Hanstein  has  shown,  in  certain  plants  (Solan acea3,  Asclep- 
iadeoe,  etc.,)  sieve-cells  penetrate  the  pith  unaccompanied 
by  any  other  elements  of  the  vascular  bundle,  and  girdled 
twigs  of  these  plants  grow  above  as  well  as  beneath  the 
wound,  although  all  leaves  above  the  girdled  place  be  cut 
off,  so  that  the  nutriment  of  the  buds  must  come  from  be 
low  the  incision. 

The  substances  which  are  organized  in  the  foliage  of  a 
plant,  as  well  as  those  which  are  imbibed  by  the  roots, 
move  to  any  point  where  they  can  supply  a  want.  Car 
bohydrates  pass  from  the  leaves,  not  only  downwards,  to 
nourish  new  roots,  but  upwards,  to  feed  the  buds,  flowers, 
and  fruit.  In  case  of  cereals,  the  power  of  the  leaves  to 
gather  and  organize  atmospheric  food  nearly-or  altogether 
ceases  as  they  approach  maturity.  The  seed  grows  at  the 
expense  of  matters  previously  stored  in  the  foliage  and 
stems  (p.  218,)  to  such  an  extent  that  it  may  ripen  quite 
perfectly  although  the  plant  be  cut  when  the  kernel  is  in 
the  milk,  or  even  earlier,  while  the  juice  of  the  seeds  is 
still  watery  and  before  starch-grains  have  begun  to  form. 

In  biennial  root-crops,  the  root  is  the  focus  of  motion 
for  the  matters  organized  by  growth  during  the  first  year ; 
but  in  the  second  year  the  stores  of  the  root  are  com 
pletely  exhausted  for  the  support  of  flowers  and  seed,  so 
that  the  direction  of  the  movement  of  these  organized 
matters  is  reversed.  In  both  years  the  motion  of  water  is 
always  the  same,  viz.,  from  the  soil  upwards  to  the  leaves.* 

The  summing  up  of  the  whole  matter  is  that  the  nutri- 


*  The  motion  of  water  is  always  upwards  because  the  soil  always  contains 
more  water  than  the  air.  If  a  plant  were  so  situated  that  its  roots  should 
Bteadily  lack  water  while  its  foliage  had  an  excess  of  this  liquid,  it  cannot  bo 
doubted  that  then  the  "  sap  "  would  pass  down  in  a  regular  flow.  In  this  case, 
nevertheless,  the  nutrient  matters  would  take  their  normal  course. 

15* 


346  HOW   CROPS    GROW. 

ent  substances  in  the  plant  are  not  absolutely  confined  to 
any  path,  and  may  move  in  any  direction.  The  fact  that 
they  chiefly  follow  certain  channels,  and  move  in  this  or 
that  direction,  is  plainly  dependent  upon  the  structure 
and  arrangement  of  the  tissues,  on  the  sources  of  nutri 
ment,  and  on  the  seat  of  growth  or  other  action. 


THE    CAUSES    OF    MOTION    OF    THE    VEGETABLE   JUICES. 

Porosity  of  Vegetable  Tissues,  —  Porosity  is  an  uni 
versal  property  of  massive  bodies.  The  word  porosity 
implies  that  the  molecules  or  smallest  particles  of  matter 
are  always  separated  from  each  other  by  a  certain  space. 
In  a  multitude  of  cases  bodies  are  visibly  porous.  In 
many  more  we  can  see  no  pores,  even  by  the  aid  of  the 
highest  magnifying  powers  of  the  microscope  ;  nevertheless 
the  fact  of  porosity  is  a  necessary  inference  from  another 
fact  which  may  be  observed,  viz.,  that  of  absorption.  A 
fiber  of  linen,  to  the  unassisted  eye,  has  no  pores.  Under 
the  microscope  we  find  that  it  is  a  tubular  cell,  the  bore 
being  much  less  than  the  thickness  of  the  walls.  By  im 
mersing  it  in  water  it  swells,  becomes  more  transparent, 
and  increases  in  weight.  If  the  water  be  colored  by  solu 
tion  of  indigo  or  cochineal,  the  fiber  is  visibly  penetrated 
by  the  dye.  It  is  therefore  porous,  not  only  in  the  sense 
of  having  an  interior  cavity  which  becomes  visible  by  a 
high  magnifying  power,  but  likewise  in  having  throughout 
its  apparently  imperforate  substance  innumerable  channels 
in  which  liquids  can  freely  pass.  In  like  manner,  all  the 
vegetable  tissues  are  more  or  less  porous  and  penetrable 
to  water. 

Imbibition  of  Liquids  by  Porous  Bodies,—  Xot  only  do 
the  tissues  of  the  plant  admit  of  the  access  of  water  into 


CAUSES    OF   THE    MOTION    OF   JUICES.  347 

their  pores,  but  they  forcibly  drink  in  or  absorb  this  liquid^ 
when  it  is  presented  to  them  in  excess,  until  their  porea 
are  full. 

When  the  molecules  of  the  porous  body  have  freedom 
of  motion,  they  separate  from  each  other  on  imbibing  a 
liquid ;  the  body  itself  swells.  Even  powdered  glass  or 
fine  sand  perceptibly  increases  in  bulk  by  imbibing  water. 
Clay  swells  much  more.  Gelatinous  silica,  pectin,  gum 
tragacanth,  and  boiled  starch,  hold  a  vastly  greater 
amount  of  water  in  their  pores. 

In  case  of  vegetable  and  animal  tissues,  or  membranes, 
we  find  a  greater  or  less  degree  of  expansibility  from  the 
same  cause,  but  here  the  structural  connection  of  the 
molecules  puts  a  limit  to  their  separation,  and  the  result 
of  saturating  them  with  a  liquid  is  a  state  of  turgidity 
and  tension,  which  subsides  to  one  of  yielding  flabbiness 
when  the  liquid  is  partially  removed. 

The  energy  with  which  vegetable  matters  imbibe  water 
may  be  gathered  from  a  well-known  fact.  In  granite 
quarries,  long  blocks  of  stone  are  split  out  by  driving 
plugs  of  dry  wood  into  holes  drilled  along  the  desired  line 
of  fracture  and  pouring  water  over  the  plugs.  The  liquid 
penetrates  the  wood  with  immense  force,  and  the  toughest 
rock  is  easily  broken  apart. 

The  imbibing  power  of  different  tissues  and  vegetable 
matters  is  widely  diverse.  In  general,  the  younger  or 
gans  or  parts  take  up  water  most  readily  and  freely.  The 
sap-wood  of  trees  is  far  more  absorbent  than  the  heart- 
wood  and  bark.  The  cuticle  of  the  leaf  is- often  compara 
tively  impervious  to  water.  Of  the  proximate  elements 
we  have  cellulose  and  starch-grains  able  to  retain,  even 
when  air-dry,  10-15°  |0  of  water.  Wax  and  the  solid  fats, 
as  well  as  resins,  on  the  contrary,  do  not  greatly  attract 
water,  and  cannot  easily  be  wetted  with  it.  They  render 
cellulose,  which  lias  been  impregnated  with  them,  unal> 
iorbent. 


348  HOW   CROPS   GROW. 

Those  vegetable  substances  which  ordinarily  manifest 
the  greatest  absorbent  power  for  water,  are  pectin,  pectic 
and  pectosic  acids,  vegetable  mucilage,  bassorin,  and  al 
bumin.  In  the  living  plant  the  protoplasmic  membrane 
exhibits  great  absorbent  power.  Of  mineral  matters, 
gelatinous  silica  (Exp.  58,  p.  123)  is  remarkable  on  account 
of  its  attraction  for  water. 

Not  only  do  different  substances  thus  exhibit  unlike  ad 
hesion  to  water,  but  the  same  substance  deports  itself  va 
riously  towards  different  liquids. 

100  parts  of  dry  ox-bladder  were  found  by  Liebig  to 
absorb  during  24  hours  : — 

268  parts  of  pure  Water. 
133     "      "   Saturated  brine. 
'38     "      "   Alcohol  (84°  |0.) 
17     "      "   Bone-oil. 

A  piece  of  dry  leather  will  absorb  either  oil  or  water, 
and  apparently  with  equal  avidity.  If,  however,  oiled 
leather  be  immersed  in  water,  the  oil  is  gradually  and 
perfectly  displaced,  as  the  farmer  well  knows  from  his  ex 
perience  with  greased  boots.  India-rubber,  on  the  other 
hand,  is  impenetrable  to  water,  while  oil  of  turpentine  is 
imbibed  by  it  in  large  quantity,  causing  the  caoutchouc 
to  swell  up  to  a  pasty  mass  many  times  its  original  bulk. 

The  absorbent  power  is  influenced  by  the  size  of  the 
pores.  Other  things  being  equal,  the  finer  these  are,  the 
greater  the  force  with  which  a  liquid  is  imbibed.  This  is 
shown  by  what  has  been  learned  from  the  study  of  a 
kind  of  pores  whose  effect  admits  of  accurate  measure 
ment.  A  tube  of  glass,  with  a  narrow,  uniform  caliber,  is 
such  a  pore.  In  a  tube  of  1  millimeter,  (about  7/3  of  an 
inch)  in  diameter,  water  rises  30  mm.  In  a  tube  of  ,'ff  mil 
limeter,  the  liquid  ascends  300  mm.,  (about  11  inches) ; 
and  in  a  tube  of  -,  »„  mm.  a  column  of  3,000  mm.  is  sus 
tained.  In  porous  bodies,  like  chalk,  plaster  stucco,  closely 
packed  ashes  or  starch,  Jamin  found  that  water  was 


CAUSES    OP   THE    MOTION    OF   JUICES. 

absorbed  with  force  enough  to  overcome  thA  jjreg&ure  of 
the  atmosphere  from  three  to  six  times ;  in  other  words— 
to  sustain  a  column  of  water  in  a  wide  tube  T0(V  to  200  ft. 
high.  (Comptes  Rendus,  50,  p.  311. 

Absorbent  power  is  influenced  by  temperature.  ,  Warra 
water  is  absorbed  by  wood  more  quickly  and  abundantly 
than  cold.  In  cold  water  starch  does  not  swell  to  airy- 
striking  or  even  perceptible  degree,  although  considerable 
liquid  is  imbibed.  In  warm  water,  however,  the  case  is 
remarkably  altered.  The  starch-grains  are  forcibly  burst 
open,  and  a  paste  or  jelly  is  formed  that  holds  many  times 
its  weight  of  water.  (Exp.  27,  p.  65.)  On  freezing,  the 
particles  of  water  are  mostly  withdrawn  from  their  adhe 
sion  to  the  starch.  The  ascent  of  liquids  in  narrow  tubes 
whose  walls  are  mi-absorbent,  is,  on  the  contrary,  dimin 
ished  by  a  rise  of  temperature. 

Adhesive  or  Capillary  Attraction. — The  absorption  of 
a  liquid  into  the  cavities  of  a  porous  body,  as  well  as  it? 
rise  in  a  narrow  tube,  are  but  expressions  of  the  general 
fact  that  there  is  an  attraction  between  the  molecules  of 
the  liquid  and  the  solid.  In  its  simplest  manifestation 
this  attraction  exhibits  itself  as  Adhesion,  and  this  term 
we  shall  employ  to  designate  the  kind  of  force  under  con 
sideration.  If  a  clean  plate  of  glass  be  dipped  in  water, 
the  liquid  touches,  and  sticks  to,  the  glass.  On  withdraw 
ing  the  glass,  a  film  of  water  comes  away  with  it.  If  two 
squares  of  glass  be  set  up  together  upon  a  plate,  so  that 
they  shall  be  in  contact  at  their  vertical  edges  on  one  side, 
and  one-eighth  of  an  inch  apart  on  the  other,  it  will  be 
seen,  on  pouring  a  little  water  upon  the  plate,  that  this 
liquid  rises  in  the  space  between  them  several  inches  or 
feet  where  they  are  in  very  near  proximity,  and  curves 
downwards  to  their  base  where  the  interval  is  large. 

Capillary  attraction — the  common  designation  of  the 
force  that  causes  liquids  to  rise  in  fine  tubes — is  the  same 
adhesion  which  is  manifested  in  all  the  cases  of  absorp 


850  HOW   CROPS   GROW. 

tiou,  which  have  been  alluded  to.  In  many  phenomena 
of  absorption,  however,  chemical  affinity  appears  to  super 
vene  with  more  or  less  vigor. 

Adhesive  attraction  is  not  manifested  universally  be 
tween  solids  and  liquids,  as  already  hinted.  Glass  dipped 
in  mercury  is  not  touched  or  wetted  by  it,  and  when  a 
capillary  tube  is  plunged  in  this  liquid,  we  see  no  rise,  but 
a  depression  within  the  bore.  A  greased  glass  tube  de 
ports  itself  similarly  towards  water. 

Adhesion  may  be  a  Cause  of  Continual  Movement  un 
der  certain  circumstances.  When  a  new  cotton  wick  is 
dipped  into  oil,  the  motion  of  the  oil  may  be  followed  by 
the  eye,  as  it  slowly  ascends,  until  the  pores  are  filled. 
At  this  moment  the  adhesive  attraction  between  cotton 
and  oil  is  satisfied,  and  motion  ceases.  Any  cause  which 
removes  oil  from  the  pores  at  the  apex  of  the  wick  will  un- 
satisfy  their  attraction  and  disturb  the  equilibrium  which 
had  been  established  between  the  solid  and  the  liquid.  A 
burning  match  held  to  the  wick,  by  its  heat  destroys  the 
oil,  molecule  after  molecule,  and  this  process  becomes  per 
manent  when  the  wick  is  lighted.  As  the  pores  at  the 
base  of  the  flame  give  up  oil  to  the  latter,  they  fill  them 
selves  again  from  the  pores  beneath,  and  the  motion  thus 
set  up  propagates  itself  to  the  oil  in  the  vessel  below  and 
continues  as  long  as  the  flame  burns  or  the  oil  holds  out. 

In  this  process,  the  pores,  if  of  the  same  material  and 
of  equal  size,  exert  everywhere  an  equal  attraction  for 
the  molecules  of  oil.  The  wick,  above,  contains  indeed 
less  oil  than  below,  for  two  reasons.  In  the  first  place, 
gravitation,  or  the  earth's  attraction,  acts  most  power 
fully  on  the  oil  below,  and  secondly,  time  is  required 
for  the  particles  of  oil  to  pass  upwards,  and  they  cannot 
reach  the  summit  as  rapidly  as  they  might  be  consumed. 
We  get  a  further  insight  into  the  nature  of  this  motion 
when  we  consider  what  happens  after  the  oil  has  all  been 
•linked  up  into  the  wick.  Shortly  thereafter  the  dimon- 


CAUSES    OF   THE    MOT1OX    OF   JUICES.  351 

sions  of  the  flame  are  seen  to  dimmish.  It  does  uot,  how- 
over  go  out,  but  burns  on  for  a  time  with  continually  do- 
creasing  vigor.  When  the  supply  of  liquid  in  the  pon-us 
body  is  insufficient  to  saturate  the  latter,  there  is  still  the 
same  tendency  to  equalization  and  equilibrium.  If,  at 
last,  when  the  flame  expires,  because  the  combustion  of 
the  oil  falls  below  that  rate  which  is  needful  to  generate 
heat  sufficient  to  decompose  it,  the  wick  be  placed  in  con 
tact  at  a  single  point,  with  another  dry  wick  of  equal 
mass  and  porosity,  the  oil  remaining  in  the  first  will  enter 
again  into  motion,  will  pass  into  the  second  wick,  from 
pore  to  pore,  until  equilibrium  is  again  restored  and  the 
oil  has  been  shared  equally  between  them. 

In  case  of  water  contained  in  the  cavities  of  a  porous 
body,  evaporation  from  the  surface  of  the  latter  becomes 
remotely  the  cause  of  a  continual  upward  motion  of  the 
liquid. 

The  exhalation  of  water  as  vapor  from  the  foliage  of  a 
plant  thus  necessitates  the  entrance  of  water  as  liquid  at 
the  roots,  and  maintains  a  flow  of  it  in  the  sap-ducts,  or 
causes  it  to  pass  by  absorption  from  cell  to  cell. 

Liquid  Diffusion* — The  movements  that  proceed  in 
plants,  when  exhalation  is  out  of  the  question,  viz.,  such 
as  are  manifested  in  the  stump  of  a  vine  cemented  into  a 
guage,  (fig.  43,  p.  248,)  are  not  to  be  accounted  for  by 
capillarity  or  mere  absorptive  for.ce  under  the  conditions 
as  yet  noticed.  To  approach  their  elucidation  we  require 
to  attend  to  other  considerations. 

The  particles  of  many  different  kinds  of  liquids  attract 
each  other.  Water  and  alcohol  may  be  mixed  together 
in  all  proportions  in  virtue  of  their  adhesive  attraction. 
If  we  fill  a  vial  with  water  to  the  rim  and  carefully  lower 
it  to  the  bottom  of  a  tall  jar  of  alcohol,  we  shall  find  after 
some  hours  that  alcohol  has  penetrated  the  vial,  and  water 
has  passed  out  into  the  jar,  notwithstanding  the  latter 
liquid  is  considerably  heavier  than  the  former.  If  the  wa- 


352  HOW   CROPS    GROW. 

ter  be  colored  by  indigo  or  cherry  jidce,  its  motion  may 
be  followed  by  the  eye,  and  after  a  certain  lapse  of  time 
the  water  and  alcohol  will  be  seen  to  have  become  uni 
formly  mixed  throughout  the  two  vessels.  This  manifesta 
tion  of  adhesive  attraction  is  termed  Liquid  Diffusion. 

What  is  true  of  two  liquids  likewise  holds  for  two 
solutions,  i.  e.,  for  two  solids  made  liquid  by  the  action  of 
a  solvent.  A  vial  filled  with  colored  brine,  or  syrup,  and 
placed  in  a  vessel  of  water,  will  discharge  its  contents  in 
to  the  latter,  itself  receiving  water  in  return  ;  and  this  mo 
tion  of  the  liquids  will  not  cease  until  the  whole  is  uni 
form  in  composition,  i.  e.,  until  every  molecule  of  salt  or 
sugar  is  equally  attracted  by  all  the  molecules  of  water. 

When  several  or  a  large  number  of  soluble  substances 
are  placed  together  in  water,  the  diffusion  of  each  one 
throughout  the  entire  liquid  will  go  on  in  the  same  way 
until  the  mixture  is  homogeneous. 

Liquid  Diffusion  may  be  a  Cause  of  Continual  Move 
ment  whenever  circumstances  produce  continual  disturb 
ances  in  the  composition  of  a  solution  or  in  that  of  a  mix 
ture  of  liquids. 

If  into  a  mixture  of  two  liquids  we  introduce  a  solid 
body  which  is  able  to  combine  chemically  with,  and  solid 
ify  one  of  the  liquids,  the  molecules  of  this  liquid  will  be- 
gin  to  move  toward  the  solid  body  from  all  points,  and 
this  motion  will  cease  only  when  the  solid  is  able  to  com 
bine  with  no  more  of  the  one  liquid,  or  no  more  remains 
for  it  to  unite  with.  Thus,  when  quicklime  is  placed  in  a 
mixture  of  alcohol  and  water,  the  water  is  in  time  com 
pletely  condensed  in  the  lime,  and  the  alcohol  is  rendered 
anhydrous. 

Rate  of  Diffusion. — The  rate  of  diffusion  varies  with 
the  nature  of  the  liquids;  if  solutions,  with  their  degree 
of  concentration  and  with  the  temperature. 

Colloids  and  Crystalloids. — There  is  a  class  of  bodies 
vbose  molecules  are  singularly  inactive  in  many  respects, 


CAUSES    OF   THE    MOTION    OF   JUICES.  353 

and  have,  when  dissolved  in  water  or  other  liquid,  a  very 
low  capacity  for  diffusive  motion.  These  bodies  are 
termed  Colloids*  and  are  characterized  by  swelling  up  or 
uniting  with  water  to  bulky  masses  (hydrates)  of  gelati 
nous  consistence,  by  inability  to  crystallize,  and  by  feeble 
and  poorly-defined  chemical  affinities.  Starch,  dextrin, 
the  gums,  the  uncrystallized  albuminoids,  pectin  and  pectio 
acid,  gelatin  (glue),  tannin  and  gelatinous  silica,  are  col 
loids.  Opposed  to  these,  in  the  properties  just  specified, 
are  those  bodies  which  crystallize,  such  as  saccharose,  glu 
cose,  oxalic,  citric,  and  tartaric  acids,  and  the  ordinary 
salts. 

Other  bodies  which  have  never  been  seen  to  crystallize 
have  the  same  high  diffusive  rate ;  hence  the  class  is  term 
ed  by  Graham  Crystalloids.\ 

Colloidal  bodies,  when  »nsoluble,  are  capable  of  imbib 
ing  liquids,  and  admit  of  liquid  diffusion  through  their 
molecular  interspaces.  Insoluble  crystalloids  are,  on  the 
other  hand,  impenetrable  to  liquids  in  this  sense.  The 
colloids  swell  up  more  or  le*s,  often  to  a  great  bulk,  from 
absorbing  a  liquid :  the  volume  of  a  crystalloid  remains 
unchanged. 

In  his  study  of  the  rates  vf  diffusion  of  various  sub 
stances,  dissolved  in  water  to  the  extent  of  one  per  cent 
of  the  liquid,  Graham  found  tbv  lullowing 

APPROXIMATE    TIMES    Of     «?QUAL    DIFFUSION. 

Chlorhydric  acid,  »» ystalloid,    1. 

Chloride  of  sodium,  "  2£, 

Sugar  (cane,)  7. 

Sulphate  of  magnesia,  7. 

Albumen,  volloid,     49. 

Caramel,  "  98. 

*  From  two  Greek  words  which  signify  glue-like. 

t  We  have  already  employed  the  word  CrystaUoid  to  distingrmVi  the  amor 
phous  albuiminoids  from  their  modifications  or  combiPttiTts  whic.v  ?s.t*ent  th.t 
aspect  of  crystals,  (p.  107.)  This  use  of  the  word  was  proposed  *T  fV^eli  in 
1862.  Graham  had  employed  it,  as  opposed  to  colloid  iSrfl,  It  w*S 
be  found  that  Nageli's  crystalloids  are  crystalloid  in  Grilwi  ^  SOLUS. 


354  HOW   CROPS   GROW. 

The  table  shows  that  the  diffusive  activity  of  chlor- 
hydric  acid  through  water  is  98  times  as  great  as  that  of 
caramel,  (see  p.  73,  Exp.  29).  In  other  words,  a  molecule 
of  the  acid  will  travel  98  times  as  far  in  a  given  time  a* 
the  molecule  of  caramel. 

Osmose,*  or  Membrane  Diffusion, — When  two  miscible 
liquids  or  solutions  are  separated  by  a  porous  diaphragm, 
the  phenomena  of  diffusion  (which  depend  upon  the  mu 
tual  attraction  of  the  molecules  of  the  different  liquids  or 
dissolved  substances),  are  complicated  with  those  of  im 
bibition  or  capillarity,  and  of  chemical  affinity.  The  ad 
hesive  or  other  force  which  the  septum  is  able  to  exert 
apon  the  liquid  molecules  supervenes  upon  the  mere  dif 
fusive  tendency,  and  the  movements  may  suffer  remarka 
ble  modifications. 

If  we  should  separate  pure  water  and  a  solution  of 
common  salt  by  a  membrane  upon  whose  substance  these 
liquids  could  exert  no  action,  the  diffusion  would  proceed 
to  the  same  result  as  were  the  membrane  absent.  Mole 
cules  of  water  would  penetrate  the  membrane  on  one  side 
and  molecules  of  salt  on  the  other,  until  the  liquid  should 
become  alike  on  both.  Should  the  water  move  faster  than 
the  salt,  the  volume  of  the  brine  would  increase,  and  that 
of  the  water  would  correspondingly  diminish.  Were  the 
membrane  fixed  in  its  place,  a  change  of  level  of  the  liq 
uids  would  occur.  Graham  has  observed  that  common 
salt  actually  diffuses  into  water,  through  a  thin  membrane 
of  ox-bladder  deprived  of  its  outer  muscular  coating,  at 
very  nearly  the  same  rate  as  when  no  membrane  is  inter 
posed. 

Dutrochet  was  the  first  to  study  the  phenomena  of 
membrane  diffusion.  He  took  a  glass  funnel  with  a  long 
and  slender  neck,  tied  a  piece  of  bladder  over  the  wide 
opening,  inverted  it,  poured  in  brine  until  the  funnel  was 

•  From  a  Greek  word  meaning  impulsion. 


CAUSES    OF    THE    MOTION    OF    JUICES. 


355 


filled  to  the  neck,  and  immersed  the  bladder  in  a  vessel  of 
water.  lie  sa\v  the  liquid  rise  in  the  narro\v  tube  and  fall 
in  the  outer. vessel.  He  designated  the  passage  of  water 
into  the  funnel  as  endosmose,  or  inward  propulsion.  At 
the  same  time  he  found  the  water  surrounding  the  funnel 
to  acquire  the  taste  of  salt.  The  outward  transfer  of  salt 
was  his  exosmose.  The  more  general  word,  Osmose,  ex 
presses  both  phenomena ;  we  may,  however,  employ  Du- 
trochet's  terms  to  designate  the  direction  of  osmose. 

Osmometer. —  When  the  apparatus  employed  by  Du- 
trochet  is  so  constructed  that  the  size  of 
the  narrow  tube  has  a  known  relation 
to,  is,  for  example,  exactly  TV  that  of  the 
membrane,  and  the  narrow  tube  itself  is 
provided  with  a  millimeter  scale,  we 
have  the  Osmometer  of  Graham,  fig.  G7. 
The  ascent  or  descent  of  the  liquid  in 
the  tube  gives  a  measure  of  the  amount 
of  osmose,  provided  the  hydrostatic  pres 
sure  is  counterpoised  by  making  the  level 
of  the  liquid  within  and  without  equal, 
for  which  purpose  water  is  poured  into 
or  removed  from  the  outer  vessel. 
Graham  designates  the  increase  of  vol 
ume  in  the  csmometer  as  positive  osmose, 
or  simply  osmose,  and  distinguishes  the 
fall  of  liquid  in  the  narrow  tube  as  nega 
tive  osmose. 

In  the  figure,  the  external  vessel  i;  intended  for  the  reception  of  w.v- 
ter.  The  funnel-shaped  interior  vessel  is  closed  below  with  membrane, 
and  stands  upon  a  shelf  of  perforated  zinc  for  support.  The  graduated 
tube  tits  the  neck  of  the  funnel  by  a  ground  joint. 

Action  Of  the  Membrane. — \V~hen  the  membrane  itself 
has  an  attraction  for  one  or  more  of  the  substances  between 
which  it  is  interposed,  then  the  rate,  amount,  and  even  di 
rection,  of  diffusion  may  be  greatly  changed. 


Fiir.  07. 


356  HOW   CROPS    GROW. 

Water  is  imbibed  by  the  membrane  of  bladder  much 
more  freely  than  alcohol ;  on  the  other  hand,  a  film  of 
collodion  (nitre-cellulose  left  from  the  evaporation  of  its 
solution  in  ether,)  is  penetrated  much  more  easily  by  alco 
hol  than  by  water.  If  now  these  liquids  be  separated  by 
bladder,  the  apparent  flow  will  be  towards  the  alcohol; 
but  if  a  membrane  of  collodion  divide  them,  the  more 
rapid  motion  will  be  into  the  water. 

When  a  vigorous  chemical  action  is  exerted  upon  the 
membrane  by  the  liquid  or  the  dissolved  matters,  osmose 
is  greatly  heightened.  In  experiments  with  a  septum  of 
porous  earthenware  (porcelain  biscuit,)  Graham  found 
that  in  case  of  neutral  organic  bodies,  as  sugar  and  alco 
hol,  or  neutral  salts,  like  the  alkali-chlorides  and  nitrates, 
very  little  osmose  is  exhibited,  i.  e.,  the  diffusion  is  not 
perceptibly  greater  than  it  would  be  in  absence  of  the 
porous  diaphragm. 

The  acids, — oxalic,  nitric,  and  chlorhydric, — manifest  a 
sensible  but  still  moderate  osmose.  Sulphuric  and  phos 
phoric  acids,  and  salts  having  a  decided  alkaline  or  acid 
reaction,  viz.,  acid  oxalate  of  potash,  phosphate  of  soda, 
and  carbonates  of  potash  and  soda,  exhibit  a  still  more 
vigorous  osmose.  For  example,  a  solution  of  one  part  of 
carbonate  of  potash  in  1,000  p:irts  of  water  gains  volume 
rapidly,  and  to  one  part  of  the  salt  that  passes  into  the 
water  500  parts  of  water  enter  the  solution. 

In  all  cases  where  diffusion  is  greatly  modified  by  a 
membrane,  the  membrane  itself  is  strongly  attacked  and 
altered,  or  dissolved,  by  the  liquids.  When  animal  mem 
brane  is  used,  it  constantly  undergoes  decomposition  and 
its  osmotic  action  is  exhaustible.  In  case  earthenware  is 
employed  as  a  diaphragm,  lime  and  alumina  are  always 
found  in  the  solutions  upon  which  it  exerts  osmose.  • 

Graham  asserts  that  to  induce  osmose  in  bladder,  the 
chemical  action  on  the  membrane  must  be  different  on  the 
two  sides,  and  apparently  not  in  degree  only,  but  n)«*  in 


CAUSES    OF   THE    MOTION    OF    JUICES.  357 

kind,  viz.,  an  alkaline  action  on  the  albuminoid  substance 
of  the  membrane  on  the  one  side,  and  an  acid  action  on 
the  other.  The  water  appears  always  to  accumulate  on 
the  alkaline  or  basic  side  of  the  membrane.  Hence  with 
an  alkaline  salt,  like  carbonate  of  potash,  in  the  osmometer, 
and  water  outside,  the  flow  is  inwards ;  but  with  an  acid 
in  the  osmometer,  there  is  negative  osmose  or  the  flow  is 
outwards,  the  liquid  then  falling  in  the  tube. 

Osmotic  activity  is  most  highly  manifested  in  such  salts 
as  easily  admit  of  decomposition  with  the  setting  free  of 
a  part  of  their  acid,  or  alkali. 

IS  yd  rut  ion  of  the  membrane. — It  is  remarkable  that 
the  rapid  osmose  of  carbonate  of  potash  and  other  alkali- 
salts  is  greatly  interfered  with  by  common  salt,  is,  in  fact, 
reduced  to  almost  nothing  by  an  equal  quantity  of  this 
substance.  In  this  case  it  is  probable  that  the  physical 
effect  of  the  salt  in  diminishing  the  power  of  the  membrane 
to  imbibe  water  (p.  348,)  operates  in  a  sense  inverse  to,  and 
neutralizes  the  chemical  action  of  the  carbonate.  In  fact, 
the  osmose  of  the  carbonate,  as  well  as  of  all  other  salts, 
ricid  or  alkaline,  may  be  due  to  their  effect  in  modifying 
the  hydration  *  or  power  of  the  membrane  to  imbibe  the 
liquid  which  is  the  vehicle  of  their  motion.  Graham  sug 
gests  this  view  as  an  explanation  of  the  osmotic  influence 
of  colloid  membranes,  and  it  is  not  unlikely  that  in  case 
of  earthenware,  the  chemical  action  may  exert  its  effect 
indirectly,  viz.,  by  producing  hydrated  silicates  from  the 
burned  clay,  which  are  truly  colloid  and  analogous  to  ani 
mal  membranes  in  respect  of  imbibition.  Graham  has 
shown  a  connection  between  the  hydrating  effect  of  acids 
and  alkalies  on  colloid  membranes  and  their  osmotic  rate. 

"It  is  well  known  that  fibrin,  albumin  and  animal  mem- 

\>rane,swell  much  more  in  very  dilute  acids  and  alkalies,  than 

i  pure  water.     On  the  other  hand,  when  the  proportion  of 

In  case  water  is  employed  as  the  liquid. 


358  HOW    CROPS    GROW. 

acid  or  alkali  is  carried  beyond  a  point  peculiar  to  each 
substance,  contraction  of  the  colloid  takes  place.  The 
colloids  just  named  acquire  the  power  of  combining  with 
an  increased  proportion  of  water  and  of  forming  higher 
gelatinous  hydrates  in  consequence  of  contact  with  dilute 
acid  or  alkaline  reagents.  Even  parchment-paper  is  more 
elongated  in  an  alkaline  solution  than  in  pure  water. 
When  thus  hydrated  and  dilated,  the  colloids  present  an 
extreme  osmotic  sensibility." 

An  illustration  of  membrane-diffusion  which  is  highly 
instructive  and  easy  to  produce,  is  the  following : 

A  cavity  is  scooped  out  in  a  carrot,  as  in  fig.  68,  so  that 
the  sides  remain  £  inch  or  so  thick,  and  a 
quantity  of  dry,  crushed  sugar  is  introduced ; 
after  some  time,  the  previously  dry  sugar  will 
be  converted  into  a  syrup  by  withdrawing 
water  from  the  flesh  of  the  carrot.     At  the 
same  time  the  latter  will  visibly  shrink  from 
the  loss  of  a  portion  of  its  liquid  contents.     In 
this  case  the  small  portions  of  juice  moistening 
the  cavity  form   a  strong  solution  with   the 
sugar  in  contact  with  them,  into  which  water  diffuses  from 
the  adjoining  cells.     Doubtless,  also,  sugar  penetrates  the 
parenchyma  of  the  carrot. 

In  the  same  manner,  sugar,  when  sprinkled  over  thin- 
skinned  fruits,  shortly  forms  a  syrup  with  the  \vater  which 
it  thus  withdraws  from  them,  and  salt  packed  with  fresh 
meat  runs  to  brine  by  the  exosmose  of  the  juices  of  the 
flesh.  In  these  cases  the  fruit  and  the  meat  shrink  as  a 
result  of  the  loss  of  water. 

(iraham  observed  gum  tragacanth,  which  is  insoluble  in 
water,  to  cause  a  rapid  passage  of  water  through  a  mem- 
br.mc  in  the  samo  manner  from  its  power  of  imbibition, 
:ilili!>ugh  here  there  could  be  no  exosmose  or  outward 
movement. 

The  application  of  ihc^'  fads  an  1  principles  to  explain- 


CAUSES    OF   THE   MOTION    OF   JUICES.  359 

ing  the  movements  of  the  liquids  of  the  plant  is  obvious. 
The  cells  and  the  tissues  composed  of  cells  furnish  pre 
cisely  the  conditions  for  the  manifestation  of  motion  by 
the  imbibition  of  liquids  and  by  simple  diffusion,  as  well  as 
by  osmose.  The  constant  disturbances  needful  to  main 
tain  constant  motion  are  to  be  found  in  fully  adequate  de 
gree  in  the  chemical  changes  that  accompany  the  process 
es  of  nutrition.  The  substances  that  normally  exist  in  the 
vegetable  cells  are  numerous,  and  they  suffer  remarkable 
transformations  both  in  chemical  constitution  and  in  physi 
cal  properties.  The  rapidly  diffusible  salts  that  are  pre 
sented  to  the  plant  by  the  soil,  and  the  equally  diffusible 
sugar  and  organic  acids  that  are  generated  in  the  leaf-cells, 
are,  in  part,  converted  into  the  sluggish,  soluble" colloids, 
soluble  starch,  dextrin,  albumin,  etc.,  or  are  deposited  as 
solid  matters  in  the  cells  or  upon  their  walls,  Thus  the 
diffusible  contents  of  the  plant  not  only,  but  the  mem 
branes  which  occasion  and  direct  osmose,  are  subject  to 
perpetual  alterations  in  their  nature.  More  than  this,  the 
plant  grows;  new  cells,  new  membranes,  new  proportions 
of  soluble  and  diffusible  matters,  are  unceasingly  brought 
into  existence.  Imbibition  in  the  cell-membranes  and 
their  solid,  colloid  contents,  Diffusion  in  the  liquid  con  • 
tents  of  the  individual  cells,  and  Osmose  between  the  liq 
uids  and  dissolved  matters  and  the  membranes,  or  colloid 
contents  of  the  cells,  must  unavoidably  take  place. 

That  we  cannot  follow  the  details  of  these  kinds  of  ac 
tion  in  the  plant  does  not  invalidate  the  fact  of  their  opera 
tion.  The  plant  is  so  complicated  and  presents  such  a 
number  and  variety  of  changes  in  its  growth,  that  we  can 
never  expect  to  understand  all  its  mysteries.  From  what 
has  been  briefly  explained,  we  can  comprehend  some  of 
the  more  striking  or  obvious  movements  that  proceed  in 
the  vegetable  organism. 

Absorption  and  Osmose  in  Germination, — The  absorp- 
tion  of  water  by  the  seed  is  the  first  step  in  Germinatioru 


360  HOW   CROPS   GROW. 

The  coats  of  the  dry  seed  when  put  into  the  moist  soft 
imbibe  this  liquid  which  follows  the  cell-walls,  from  cell 
to  cell,  until  these  membranes  are  saturated  and  swollen. 
At  the  same  time  these  membranes  occasion  or  permit  os 
mose  into  the  cell-cavities,  which,  dry  before,  become  dis 
tended  with  liquid.  The  soluble  contents  of  the  cells  or 
the  soluble  results  of  the  transformation  of  their  organized 
matters,  diffuse  from  cell  to  cell  in  their  passage  to  the  ex 
panding  embryo. 

The  quantity  of  water  imbibed  by  the  air-dry  seed  commonly  amounts 
to  50  and  may  exceed  100  per  cent.  R.  Hoffmann  has  made  observations 
on  this  subject,  (Vs.  /SY.,  VII,  p.  50.)  The  absorption  was  usually  com 
plete  in  48  or  72  hours,  and  was  as  follows  in  case  of  certain  agricultural 
plants : — 


Per  cent. 

Mustard 8.0 

Millet 35.0 

Maize 44.0 

Wheat 45.5 

Buckwheat 46.8 

Barley 48.2 

Turnip 51.0 

Rye 57.7 


Per  cent. 

Oats    59.8 

Hemp 60.0 

Kidney  Bean 96.1 

Horse  Beau 104.0 

Pea 106.8 

Clover 117.5 

Beet 120.5 

White  Clover 126.7 


Root-Action* — Absorption  at  the  roots  is  unquestiona 
bly  an  osmotic  action  exercised  by  the  membrane  that 
bounds  the  young  rootlets  and  root-hairs  externally.  In 
principle  it  does  not  differ  from  the  absorption  of  water 
by  the  seed.  The  mode  in  which  it  occasions  the  surpris 
ing  phenomena  of  bleeding  or  rapid  flow  of  sap  from  a 
wound  on  the  trunk  or  larger  roots  is  doubtless  essentially 
as  Hofmeister  first  elucidated  by  experiment. 

TliisJZow  proceeds  in  the  ducts  and  intercommunicating 
wood-cells.  Between  these  and  the  soil  intervenes  loose 
cell-tissue  surrounded  by  a  compactor  epidermis.  Osmose 
takes  place  in  the  epidermis  with  such  energy  as  not  only 
to  distend  to  its  utmost  the  cell-tissue,  but  to  cause  the 
water  of  the  cells  to  filter  through  their  walls,  and  thus 
train  nccess  to  tlio  ducts.  The  latter  are  formed  in  young 


CAUSES    OF    THE    MOTIOX    OF    JUICES. 


361 


cambial  tissue,  and  when  new,  are  very  delicate  in  their  walls. 
Fig.  69  represents  a  simple  apparatus  by  Sachs  for  imi 
tating  the  supposed  mechanism  and  process  of  Root-ac 
tion.     In  the  fig.,  g  g  represents  a  short,  wide,  open  glass 
tube ;  at  a,  the  tube  is  tied  over  and  securely 
closed  by  a  piece  of  pig's  bladder ;  it  is  then 
filled  with  solution  of  sugar,  and  the  other  end, 
£,  is  closed  in  similar  manner  by  a  piece  of  parch 
ment-paper,  (p.   59.)      Finally   a   cap   of  India- 
rubber,  If,  into  whose  neck  a  narrow,  bent  glass 
tube,  r,  is  fixed,  is  tied  on  over  b.     (These  join 
ings  must  be.  made   very  carefully  and  firmly.) 
The  space  within  r  JTis  left  empty  of  liquid,  and 
the  combination  is  placed  in  a  vessel  of  water,  as 
in  the  figure.      C  represents  a  root-cell  whose 

exterior  wall  (cuti 
cle,)  a,  is  less  pene 
trable  under  pressure 
than  its  interior,  b  ; 
r  corresponds  to  a 
duct  of  vascular  tis 
sue,  and  the  sur 
rounding  water  takes 
the  place  of  that 
existing  in  the  pores 


Fig.  69. 


of  the  soil.  The  water  shortly  penetrates  the  cell,  (7, 
distends  the  previously  flabby  membrnnes,  under  the  ac 
cumulating  tension  filters  through  b  into  r,  and  rises  in 
the  tube;  where  in  Sachs'  experiment  it  attained  a  height, 
of  4  or  5  inches  in  24  to  48  hours,  the  tube,  r,  being  about 
5  millimeters  wide  and  the  area  of  b,  700  sq.  mm.  When 
we  consider  the  vast  root-surface  exposed  to  the  soil,  in 
case  of  a  vine,  and  that  myriads  of  rootlets  and  root-hairs 
unite  their  action  in  the  comparatively  narrow  stem,  we 
must  admit  that  the  apparatus  above  figured  gives  us  c* 
very  satisfactory  glance  into  the  causes  of  bleeding. 
16 


HOW    CROPS    GROW. 

Rapid  Motion  of  Sap  in  the  Stem. — In  the  stem  of  the 
plant  we  have  commonly  a  resistance  to  root-action,  so  far 
as  a  flow  of  liquid  is  concerned.  The  ducts  and  sieve' 
cells, — in  conifers,  the  wood-cells — though  offering  visibly 
continuous  channels  for  the  transmission  of  juices,  are 
nevertheless  in  most  cases  extremely  small,  and  while  they 
r.;ise  liquids  with  enormous  capillary  force,  they  retain 
them  with  the  same  force,  and  continuous  motion  can  only 
be  the  result  of  a  correspondingly  energetic  disturbance. 
The  root-notion  which  can  sustain  a  column  of  mercury 
many  inches,  or  one  of  water  many  feet  high,  in  a  wide 
fibe,  is  greatly  neutralized  by  capillarity  as  we  ascend  the 
stem  from  the  root,  or  the  root  from  its  young  extremities. 
Hoot-action  is,  however,  unsteady  in  its  operation,  and 
when  it  declines  from  any  cause,  it  is  capillarity  which  acts 
rapidly  within  the  ducts  and  visible  channels  to  supply 
waste  by  evaporation. 

Motion  of  Nutritive  or  Dissolved  Matters:  Selective 
Power  of  the  Plant, — The  motion  of  the  substances  that 
enter  the  plant  from  the  soil  in  a  state  of  solution  and  of 
those  organized  within  the  plant  is  to  a  great  degree  sep 
arate  from  and  independent  of  that  which  the  water  itself 
takes.  At  the  same  time  that  water  is  passing  upwards 
through  the  plant  to  make  good  the  waste  by  evaporation 
from  the  foliage,  sugar  or  other  carbohydrate  generated 
in  the  leaves  is  diffusing  against  the  water,  and  finding  its 
way  down  to  the  very  root-tips.  This  diffusion  takes  place 
mostly  in  the  cell-tissue,  and  is  undoubtedly  greatly  aided 
by  osmose,  i.  e.,  by  the  action  of  the  membranes  them 
selves.  The  very  thickening  of  the  cell-walls  by  the  dep 
osition  of  cellulose  \vould  indicate  an  attraction  for  the 
material  from  which  cellulose  is  organized.  The  same 
transfer  goes  on  sirniiltan/o-isly  in  all  directions,  not  only 
into  roots  and  stem,  but  into  the  new  bti  Is,  into  flowers 
and  fruit.  We  have  considered  the  tendency  to  equaliza 
tion  between  two  masses  of  liquid  separated  from  each 


CAUSES    OF    THE    MOTION    OF    JUICES.  3(5?! 

other  by  penetrable  membranes.  This  tendency  makes 
valid  for  the  organism  of  the  plant  the  law  that  demand 
creates  supply.  In  two  contiguous  cells,  one  of  which 
contains  solution  of  sugar,  and  the  other,  solution  of  ni 
trate  tA  potash,  these  substances  must  diffuse  until  they 
arc  mingled  equally,  unless,  indeed,  the  membranes  or  some 
other  babstance  present  exerts  an  opposing  ami  prepondcr* 
aiing  attraction. 

In  the  simplest  phases  of  liffusion  each  substance  is  to 
a  certain  degree  independent  of  every  other.  Nitrate  of 
potash  dissolved  in  the  water  of  the  soil  must  diffuse  into 
the  root-cells  of  a  plant  if  it  be  absent  from  the  sap  of  this 
root-cell  and  the  membrane  permit  its  passage.  When 
the  root-cell  has  acquired  a  certain  proportion  of  nitrate 
of  potash,  a  proportion  equal  to  that  in  the  soil-water,  the 
nitrate  cannot  enter  it  any  more.  So  soon  as  a  molecule 
of  the  salt  has  gone  on  into  another  ceil  or  been  removed 
from  the  sap  by  any  chemical  transformation,  then  a  mole 
cule  may  and  must  enter  from  without. 

Silica  is  much  more  abundant  in  grasses  and  cereals  than 
in  leguminous  plants.  In  the  former  it  exists  to  the  extent 
of  about  25  parts  in  1,000  of  the  air-dry  foliage,  while  the 
leaves  and  stems  of  the  latter  contain  but  3  parts.  (See 
Wolff's  Table  in  Appendix.)  When  these  crops  grow  side 
by  side,  their  roots  are  equally  bathed  by  the  same  soil- 
water.  Silica  enters  both  alike,  and,  so  far  as  regards  it 
self,  brings  the  cell-contents  to  the  s:ime  state  of  satura 
tion  that  exists  in  the  soil.  The  cereals  are  able  to  dispose 
of  silica  by  giving  it  a  place  in  the  cuticular  cells ;  tho 
i  -guminous  crops,  on  the  other  hand,  cannot  remove  it 
Prom  their  juices;  the  latter  remain  saturated,  and  thus 
further  diffusion  of  silica  from  without  becomes  impossi 
ble  except  as  room  is  made  by  new  growth.  It  is  in  this 
way  that  we  have  a  rational  and  adequate  explanation  of 
the  selective  power  of  the  plant,  as  manifested  in  its  de 
portment  towards  the  medium  that  invests  its  roots. 


364  HOW   CROPS    GROW. 

same  principles  govern  the  transfer  of  matters  from  cell 
to  cell,  or  from  organ  to  organ,  within  the  plant.  Where- 
ever  there  is  unlike  composition  of  two  miscible  juices, 
diffusion  is  thereby  set  up,  and  proceeds  as  long  as  the 
cause  of  disturbance  lasts,  provided  impenetrable  mem 
branes  do  not  intervene.  The  rapid  movement  of  water 
goes  on  because  there  is  great  loss  of  this  liquid ;  the  slow 
motion  of  silica  is  a  consequence  of  the  little  use  that  arises 
for  it  in  the  plant. 

Strong  chemical  affinities  may  be  overcome  by  osmose. 
Graham  long  ago  observed  the  decomposition  of  alum 
(sulphate  of  alumina  and  potash,)  by  mere  diffusion ;  its 
sulphate  of  potash  having  a  higher  diffusive  rate  than  its 
sulphate  of  alumina.  In  the  same  manner  acid  sulphate 
of  potash,  put  in  contact  with  water,  separates  into  sul 
phate  of  potash  and  free  sulphuric  acid. 

We  have  seen  (pp.  170-1)  that  the  plant  when  vegetat 
ing  in  solutions  of  salts,  is  able  to  decompose  them.  It 
separates  the  components  of  nitrate  of  potash — appropriat 
ing  the  acid  and  leaving  the  base  to  accumulate  in  the 
liquid.  It  resolves  chloride  of  ammonium, — 'taking  up  am 
monia  and  rejecting  the  chlorine.  The  action  in  these 
cases,  we  cannot  definitely  explain,  but  our  analogies 
leave  no  doubt  as  to  the  general  nature  of  the  agencies 
that  cooperate  to  such  results. 

The  albuminoids  in  their  usual  form  are  colloid  bodies 
and  very  slow  of  diffusion  through  liquids.  They  pass  a 
membrane  of  nitrocellulose  somewhat  (Schumacher) ;  but 
can  scarcely  penetrate  parchment-paper.  (Graham.)  In 
the  plant  they  are  found  chiefly  in  the  sieve-cells  and  ad 
joining  parts  of  the  cambium.  Since  for  their  production, 
they  undoubtedly  require  the  concourse  of  a  carbohydrate 
and  a  nitrate,  they  are  not  unlikely  genera U'd  in  the  cam 
bium  itself,  for  here  the  descending  carbohydrates  from 
the  foliage  ccnie  in  contact  \vith  the  nitrates  as  they  rise 
from  the  soiL  On  the  other  hand,  the  albuminoids  be 


CAUSES    OF   THE    MOTION    OF   JUICES.  8G5 

come  more  diffusible  in  some  of  their  combinations. 
Schumacher  asserts  that  carbonates  and  phosphates  of  the 
alkalies  considerably  increase  the  osmose  of  albumin 
through  membranes  of  nitrocellulose,  (PhysiJc  der  Pflanze} 
p.  128.)  It  is  probable  that  those  combinations  or  modi 
fications  of  the  albuminoids  which  occur  in  the  soluble 
crystalloids  of  aleurone  (p.  105,)  and  haemoglobin  (p.  97,) 
are  highly  diffusible.  The  fact  of  their  having  the  form 
of  crystals  is  of  itself  presumptive  evidence  of  this  view, 
which  deserves  to  be  tested  by  experiment. 

Gaseous  bodies,  especially  the  carbonic  acid  and  oxygen 
of  the  atmosphere,  which  have  free  access  to  the  intercel 
lular  cavities  of  the  foliage,  and  which  are  for  the  most 
part  the  only  contents  of  tne  larger  ducts,  may  be  dis 
tributed  throughout  the  plant  by  osmose  after  having  been 
dissolved  in  the  sap  or  otherwise  absorbed  by  the  cell- 
contents. 

Influence  of  the  Membranes, — The  sharp  separation 

of  unlike  juices  and  soluble  matters  in  the  plant  indicates 
the  existence  of  a  remarkable  variety  and  range  of  ad 
hesive  attractions.  In  orange-colored  flowers  we  see  upon 
microscopic  examination  that  this  tint  is  produced  by  the 
united  effect  of  yellow  and  red  pigments  which  are  con 
tained  in  the  cells  of  the  petals.  One  cell  is  filled 
with  yellow  pigment,  and  the  adjoining  one  with  red, 
but  these  two  colors  are  never  contained  in  the  same 
cell.  In  fruits  we  have  coloring  matters  of  great  tinc 
torial  power  and  freely  soluble  in  water,  but  they  never 
forsake  the  cells  where  they  appear,  never  wander  into 
the  contiguous  parts  of  the  plant.  In  the  stems  and 
leaves  of  the  dandelion,  lettuce,  and  many  other  plants, 
a  white,  milky,  and  bitter  juice  is  contained,  but  it  is 
strictly  confined  to  certain  special  channels  and  never 
visibly  passes  beyond  them.  The  loosely  disposed  cells 
of  the  interior  of  leaves  contain  grains  of  chlorophyll, 
but  this  substance  does  not  appear  in  the  epidermal  cells, 


«'K')6  HOW   CROPS    GROW. 

those  of  the  stomata  excepted.  Sachs  found  that  solution 
of  indigo  quickly  entered  the  roots  of  a  seedling  bean, 
but  required  a  considerable  time  to  penetrate  the  stem,  (p. 
239.)  Hallier,  in  his  experiments  on  the  absorption  of 
colored  liquids  by  plants,  noticed  in  all  cases,  when  leave? 
or  green  steins  were  immersed  in  solution  of  indigo,  or 
black-cherry  juice,  that  these  dyes  readily  passed  into  and 
c.xored  the  epidermis,  the  vascular  and  cambial  tissue, 
and  the  parenchyma  of  the  leaf-veins,  keeping  strictly  to 
the  cell-walls,  but  in  no  instance  communicated  any  color 
to  the  cells  containing  chlorophyll.  (Phytopathologie, 
Leipzig,  1868,  p.  67.)  We  must  infer  that  the  coloring 
matters  either  cannot  penetrate  the  cells  that  are  occupied 
with  chlorophyll,  or  else  are  chemically  transformed  into 
colorless  substances  on  entering  them. 

Sachs  has  shown  in  numerous  instances  that  the  juices 
of  the  sieve-cells  and  cambial  tissue  are  alkaline,  while 
those  of  the  adjoining  cell-tissue  are  acid  when  examined 
by  test-paper.  (Exp.  Pliys.  der  Pflanzen,  p.  391.) 

When  young  and  active  cells  are  moistened  with  solu 
tion  of  iodine,  this  substance  penetrates  the  cellulose 
without  producing  visible  change,  but  when  it  acts  upon 
the  protoplasm,  the  latter  separates  from  the  outer  cell- 
wall  and  collapses  towards  the  center  of  the  cavity,  .^s  if 
its  contents  passed  out,  without  a  corresponding  endos- 
mose  being  possible,  (p.  224.) 

We  may  conclude  from  these  facts  that  the  membranes 
of  the  cells  are  capable  of  effecting  and  maintaining  the 
separation  of  substances  which  have  considerable  attrac 
tions  for  each  other,  and  obviously  accomplish  this  result 
by  exerting  themselves  superior  attractive  or  repulsive 
force. 

The  influence  of  the  membrane  must  vary  in  character 
with  those  alterations  in  its  chemical  and  structural  consti 
tution  which  result  from  growth  or  any  other  cause.  It  is 
thus,  in  part,  that  the  assimilation  of  external  f  >od  by  the 


MECHANICAL  EFFECTS  OF  OSMOSE  OX   THE    PLANT.    367 

plant  is  directed,  now  more  to  one  class  of  proximate  in 
gredients,  as  the  carbohydrates,  and  no\v  to  another,  as  the 
albuminoids,  although  the  supplies  of  food  presented  are 
uniform  both  in  total  and  relative  quantity. 

If  a  slice  of  red-beet  be  washed  and  put  into  writer,  the 
pigment  which  gives  it  color  does  not  readily  dissolve  and 
diffuse  out  of  the  cells,  but  the  water  remains  colorless  for 
several  days.  The  pigment  is,  however,  soluble  in  water, 
as  is  seen  at  once  by  crushing  the  beet,  whereby  the  cells 
are  forcibly  broken  open  and  their  contents  displaced. 
The  cell-membranes  of  the  uninjured  root  are  thus  appar 
ently  able  to  withstand  the  solvent  power  of  water  upon 
the  pigment  and  to  restrain  the  latter  from  diffusive  mo 
tion.  Upon  subjecting  the  slice  of  beet  to  cold  until  it  is 
thoroughly  frozen,  and  then  placing  it  in  warm  water  so 
that  it  quickly  thaws,  the  latter  is  immediately  and  deeply 
tinged  with  red.  The  sudden  thawing  of  the  water  with 
in  the  pores  of  the  cell-membrane  has  in  fact  so  altered 
them,  that  they  can  no  longer  prevent  the  diffusive  ten 
dency  of  the  mgment.  (Sachs.) 

§4. 
MECHANICAL  EFFECTS  OF  OSMOSE  ON  THE  PLANT. 

The  osmose  of  water  from  without  into  the  cells  of  the 
plant,  whether  occurring  on  the  root-surface,  in  the  buds, 
or  at  any  intermediate  point  where  chemical  changes  are 
going  on,  cannot  fail  to  exercise  a  great  mechanical  influ 
ence  on  the  phenomena  of  growth.  Root-action,  for  ex 
ample,  being,  as  we  have  seen,  often  sufficient  to  overcome 
a  considerable  hydrostatic  pressure,  might  naturally  be 
expected  to  accelerate  the  development  of  buds  and  young 
foliage,  especially  since,  as  common  observation  shows,  it 
operates  in  perennial  plants,  as  the  maple  and  grape-vine, 
most  energetically  at  the  season  when  the  issue  of  foliage 
takes  place.  Experiment  demonstrates  this  to  be  the  fact. 


368 


HOW    CROPS    GROW. 


If  a  twig  be  cut  from  a  tree  in  winter 
and  be  placed  in  a  room  having  a  summer 
temperature,  the  bii'ls,  before  dormant, 
shortly  exhibit  signs  of  growth,  and  if 
the  cut  end  be  immersed  in  water,  the 
buds  will  enlarge  quite  after  the  normal 
manner,  as  long  as  the  nutrient  matters 
of  the  twig  last,  or  until  the  tissues  at 
the  cut  begin  to  decay.  It  is  the  summer 
temperature  which  excites  the  chemical 
changes  that  result  in  growth.  Water 
is  needful  to  occupy  the  expanding  and 
new-forming  cells,  and  to  be  the  vehicle 
for  the  translocation  of  nutrient  matters 
from  the  wood  to  the  buds.  .Water  en 
ters  the  cut  stem  by  imbibition  or  capil 
larity,  not  merely  enough  to  replace  loss 
by  exhalation,  but  is  sucked  in  by  osmose 
actin^  in  the  growing  cells.  Under  the 

O  O  G 

same  conditions  as  to  temperature,  the 
t \\igs  which  are  connected  with  active 
roots  expand  earlier  and  more  rapidly 
than  cuttings.  Artificial  pressure  on  the 
water  which  is  presented  to  the  latter 
acts  with  an  effect  similar  to  that  which 
the  natural  stress  caused  by  the  root- 
power  exerts.  This  fact  was  demon 
strated  by  Boehm  (Sitzungsberichfo  der  fl 
Wiener  Aknd.,  1868)  in  an  experiment 
which  may  be  made  as  illustrated  by  the 
cut,  fig.  70.  A  twig  with  buds  is  secured 
by  means  of  a  perforated  cork  into  one 
end  of  a  short,  wide  glass  tube,  which 
is  closed  below  by  another  cork  through 
which  passes  a  narrow  syphon-tube,  ./?. 
The  cut  end  of  the  twig  is  immersed  in 


MECHANICAL  EFFECTS  OF  OSMOSE  ON  THE   PLANT.    360 

water,  TFJ  which  is  put  under  pressure  by  pouring  mercury 
into  the  upper  extremity  of  the  syphon-tube.  Horse- 
chestnut  and  grape  twigs  cut  in  February  and  March  and 
thus  treated, — the  pressure  of  mercury  being  equal  to  6-8 
inches  above  the  level,  JfcT, — after  4-6  weeks,  unfolded  their 
buds  with  normal  vigor,  while  twigs  similarly  circum 
stanced  but  without  pressure  opened  4-8  days  later  and 
with  less  appearance  of  strength. 

Fr.  Schulze  (JLarsten's  Sot.  Uhters.,  Berlin,  II,  143) 
found  that  cuttings  of  twigs  in  the  leaf,  from  the  horse- 
chestnut,  locust,  willow  and  rose,  subjected  to  hydrostatic 
pressure  in  the  same  way,  remained  longer  turgesoent  and 
advanced  much  farther  in  development  of  leaves  and  flow 
ers  than  twigs  simply  immersed  in  water. 

The  amount  of  water  in  the  soil  influences  both  the  ab 
solute  and  relative  quantity  of  this  ingredient  in  the  plant. 
It  is  a  common  observation  that  rainy  spring  weather 
causes  a  rank  growth  of  grass  and  straw,  while  the 
yield  of  hay  and  grain  is  not  correspondingly  increased. 
The  root-action  must  operate  with  greater  effect,  other 
things  being  equal,  in  a  nearly  saturated  soil  than  in  one 
which  is  less  moist,  and  the  young  cells  of  a  plant  situated 
in  the  former  must  be  subjected  to  greater  internal  stress 
than  those  of  one  growing  in  the  latter — must,  as  a  con 
sequence,  attain  greater  dimensions.  It  is  not  uncommon 
to  find  fleshy  roots,  especially  radishes  which  have  grown 
in  hot-beds,  split  apart  lengthwise,  and  Hallier  mentions 
the  fact  of  a  sound  root  of  petersilia  splitting  open  after 
immersion  in  water  for  two  or  three  days.  (Phytopathol- 
offie,  p.  87.)  This  mechanical  effect  is  indeed  commonly 
conjoined  with  others  resulting  from  abundant  nutrition, 
but  increased  bulk  of  a  plant  without  corresponding  in 
crease  of  dry  matter  is  doubtless  in  great  part  the  conse 
quence  of  large  supplies  of  water  to  the  roots  and  its  vig 
orous  osmose  into  the  expanding  plant. 

16* 


370 


HOW    CROPS    GROW. 


5. 


DIRECTION  OF  VEGETABLE  GROWTH. 

One  of  the  most  obvious  peculiarities  of  vegetation  is 
that  the  roots  and  stems  of  plants  manifest  more  or  less 
regular  and  often  opposite  directions  of  growth.  Roots, 
in  general,  grow  downwards;  stems,  in  general,  upwards, 
though  this  is  by  no  means  a  universal  rule,  both  roots 
and  stems  oftentimes  manifesting  either  tendency  in  dif 
ferent  points  or  at  different  times  of  their  growth. 

Sachs  describes  the  following  mode  of  observing  the 
directive  tendency  of  root  and  stem. 

E,  fig.  71,  is  a  glass  flask  containing  some  water;  it  is 

closed  above  by  a  cork  from         

which  a  young  seedling  is 
suspended  by  means  of  a 
wire.  The  flask  stands  upon 
a  plate  of  sand,  and  it  is 
shielded  from  the  light  by  a 
paste-board  cover,  .72,  the 
lower  edge  of  which  is  forced 
down  into  the  sand.  The 
water  in  the  flask  keeps  the 
enclosed  air  in  a  moist 
state.  In  the  experiment,  a 
sprouted  nasturtium  seed 
(Tropceolum  majus)  having 
a  perfectly  straight  descend 
ing  radicle,  was  placed  at 
night  in  the  apparatus  with 


the  radicle  pointing  upwards 


Fig.  71. 


and  the  plumule  downwards.  The  next  morning  the 
seedling  had  the  appearance  of  the  figure.  During  the 
night  the  tip  of  the  root  curved  over  and  the  plumule 
sensibly  raised  itself.  By  continuing  a  similar  experiment 


CAUSES    OF    THE    MOTION    OF    JUICES.  ,">?! 

for  a  week  or  more,  the  rootlet  will  grow  down  into  the 
water  and  the  stem  will  reach  the  cork.  As  often  as  the 
position  of  the  seedling  is  reversed,  so  often  the  root  and 
stem  will  reverse  the  direction  of  their  growth.  This  ex 
periment  being  carried  on  in  total  darkness,  save  during 
the  short  intervals  necessary  for  observation,  the  directive 
tendency  is  shown  to  be  independent  of  the  action  of  light. 

Causes  of  Directive  Power. — The  direction  of  growth 

in  plants  appears  to  be  for  the  most  part  the  consequence 
of  the  action  either  of  gravitation  simply,  as  in  those 
parts  which  extend  directly  downwards,  or  of  internal 
tension  overcoming  gravitation,  as  in  the  parts  which  grow 
vertically  upwards,  or  lastly  of  a  combination  (resultant) 
of  the  two  forces  in  the  parts  which  extend  in  the  inter 
mediate  directions. 

The  parts  of  a  plant,  whether  the  individual  cells  or  ag 
gregates  of  cells,  are  either  in  a  state  of  tension  greater  or 
less  and  varying  at  different  times,  or  they  are  entirely 
passive. 

In  general,  tension  prevails  in  most  parts  of  common 
plants  ;  the  full-formed  roots,  stems,  leaves,  etc.,  maintain 
their  relative  positions  against  opposing  forces,  and  when 
bent,  recover  themselves  with  more  or  less  elasticity  and 
completeness. 

There  are,  however,  points  where  tension  is  absent  or 
equally  exerted  towards  all  sides,  and  is  hence  unable  to 
give  direction  to  growth.  This  may  be  the  case  where 
the  tissue,  consisting  exclusively  of  newly-formed  and  im 
mature  cells,  having  delicate  walls,  possesses  but  little 
firmness,  but  is  plastic  like  a  semifluid  substance.  In  such 
a  condition  of  growth  the  cells  follow  the  stress  of  gravi 
tation  or  of  any  external  force  that  may  be  accidentally 
applied. 

Influence  of  Gravitation. — Most  young  roots  are  in 
this  passive  condition  near  the  tips  in  the  region  where 


372  HOW   CROPS    GROW. 

their  elongation  occurs.  The  new  growth  at  these  points 
simply  obeys  the  attraction  of  the  earth  like  any  other 
limp  or  yielding  mass,  and  a  root  made  to  grow*  on  a 
horizontal  plate  of  glass,  for  example,  is  pushed  along  by 
the  expansion  of  its  young  cells  and  the  formation  of  new 
ones  until  it  reaches  the  edge,  when  the  tip  inclines  down 
ward  as  a  wet  string  would  do.  If,  however,  as  many 
times  happens,  the  yielding  tissue  of  new  cells  is  partially 
or  entirely  enveloped  by  the  "more  rigid  root-cap,  the 
downward  tendency  may  be  overcome  to  a  corresponding 
degree.  In  this  case  the  tip  keeps  more  or  less  closely 
the  direction  already  given  to  the  root,  resembling  in  its 
growth  a  half  melted  substance  protuded  from  a  tube  and 
stiffening  as  it  issues.  The  passive  section  of  the  root  is 
translated  forward  as  the  root  itself  extends ;  the  cells  that 
to-day  yield  to  the  gravitating  force,  to-morrow  become 
so  rigid  and  firmly  grown  to  each  other  as  to  resist  the 
tendency  of  this  force  to  coerce  them  to  a  vertical,  while 
new  cells  are  developed  beyond,  which  conform  to  the 
gravitating  tendency. 

Internal  Tension, — In  the  upward-growing  stem  the 
different  parallel  and  concentric  tissues,  viz.,  the  cuticle, 
the  cell-tissue  of  the  rind,  the  wood-cells  and  ducts,  and 
the  pith,  exist  in  a  state  of  unequal  tension. 

This  is  shown  by  well-known  facts.  If  a  hollow,  suc 
culent  stem,  like  that  supporting  a  dandelion  blossom,  be 
cut  lengthwise,  the  parts  curve  away  from  each  other, 
thus,  )(,  and  may  by  a  little  assistance  be  rolled  together 
in  Hat  ooils.  The  same  separation  of  the  halves  may  be 
observed  in  any  succulent  stem,  provided  it  be  fresh  and 
turgid.  It  is  plain  then  that  the  pith-cells  of  the  growing 
stem  are  compressed  by  the  cuticle ;  in  other  words  the 
pith-cells  are  in  a  state  of  tension,  while  the  cuticular  cells 
are  passively  stretched  by  this  interior  strain.  Closer  in 
vestigation  indicates  that  the  matter  is  somewhat  compli 
cated,  If  we  strip  off  the  "skin,"  from  a  stalk  D£  garden 


CAUSES    OF   THE    MOTION    OF   JUICES.  373 

rhubarb  (pie-plant,)  we  shall  notice  that  it  curves  to  a  coil 
or  spiral.  This  skin  consists  of  the  true  cuticle  with  a 
coating  of  cell-tissue  adhering.  The  tension  of  the  latter 
and  the  passivity  of  the  former  occasion  the  curvature. 
Further  dissection  demonstrates  that  in  general  the  cuti 
cle,  the  wood-cells,  and  the  vascular  bundles,  are  passive, 
while  the  cell-tissues  of  the  rind  and  pith,  and  the  corre 
sponding  cell-tissues  of  the  leaves,  are  tense. 

It  follows  from  these  considerations  that  the  length  of  a 
fresh  growing  stem  must  be  different  from  the  length  of 
its  parts  when  separate  from  each  other.  If  we  divide  a 
succulent  stem  lengthwise,  into  the  pith,  the  wood  and 
the  rind  or  the  corresponding  parts,  and  accurately 
measure  them,  we  shall  find  in  fact  that  they  differ  as  to 
length  from  each  other  and  from  the  stem  as  a  whole. 
The  pith,  when  the  wood  is  cut  away,  elongates,  the  wood 
shortens,  the  rind  shortens  still  more.  In  the  original 
stem  the  cell-tissue  being  united  to  the  vascular,  stretches 
the  latter  and  is  at  the  same  time  restrained  by  it.  On 
their  being  cut  apart,  the  one  is  free  to  extend  and  the 
other  to  shorten.  Sachs  gives  the  following  comparative 
measurements  of  the  stem  of  a  tobacco  plant,  and  of  its 
parts  after  separation — the  length  of  the  stem  being  as 
sumed  as  100 : 

Entire  stem   -  100 

Rind  -      94.1 

Wood  -  -  98.5 

Pith  -     102.9 

Causes  Of  Tension, — This  tense  condition  of  the  con 
siderably  developed  stem  depends  partly  upon  the  unequal 
nutrition  of  the  different  tissues.  Those  parts,  in  fact,  ex 
ert  tension  in  which  rapid  growth — cell-multiplication — is 
taking  place.  In  the  simple  cell  similar  tension  may  exist, 
caused  by  the  tendency  of  the  formative  layer  to  expand 
beyond  the  limits  of  the  cell-wall.  Another  cause  of 
tension  is  the  different  imbibing  and  osmotic  power  of  the 


374  HOW   CROPS   GROW. 

tissues  for  sap.  When  a  fresh  stem  or  leaf  loses  a  few 
per  cent  of  water,  it  becomes  flabby  and,  except  so  far  as 
supported  by  indurated  woody-tissue,  has  no  self-sustaining 
power  and  droops  from  an  upright  direction.  On  dissect 
ing  the  flabby  stem  lengthwise,  the  halves  no  longer  curve 
apart,  and  the  tension  noticed  in  the  fresh  stem  does  not 
exist.  The  water  being  restored  through  the  root,  the 
normal  turgor  and  original  position  are  both  recovered. 
In  the  cell-tissue,  the  cells  themselves,  so  long  as  tension 
manifests  itself,  are  fully  occupied  and  distended  with  sap, 
and  contain  a  highly  osmotic  protoplasm;  the  vascular 
tissues  being  the  result  of  age  and  alteration  in  the  cell- 
tissue,  are  therefore  more  rigid  in  their  walls  and  less 
sensitive  to  mechanical  strain. 

Upward  Growth, — If  a  stem  whose  terminal  parts  are 
in  a  state  of  highly  unequal  tension  be  brought  into  a 
horizontal  position,  it  will  be  found  that  as  it  makes  new 
growth  the  tip  curves  upward  until  it  becomes  vertical. 
This  is  due  to  the  fact  that  while  the  whole  growing  part 
elongates,  the  under  side  extends  most  rapidly.  Hof 
meister  has  demonstrated  that  this  curvature  is  not  the 
result  of  increased  tension  in  the  active  cell-tissue  of  the 
lower  longitudinal  section  of  the  stem,  but  of  increased 
extensibility  on  the  part  of  the  cuticular  and  vascular  tis 
sues  of  that  region,  for  on  removing  the  entire  cuticle 
from  a  curved  onion-stalk  the  curvature  was  not  increased 
but  diminished. 

The  question  now  arises,  why  do  the  passive  parts  of 
the  under  side  of  the  stem  that  is  out  of  the  vertical  n<l- 
init  of  greater  expansion  by  the  stress  of  the  rapidly 
growing  tissues,  than  those  of  the  upper?  The  only 
cause  hitherto  assigned  is  the  action  of  gravitation  on  the 
juices  of  the  tissues.  In  a  stem  inclined  from  the  verti 
cal,  the  cells  of  the  lower  side  experience  not  only  the 
general  pressure  of  the  water  which  renders  the  whole 
turgid,  but,  in  addition,  they  sustain  a  portion  of  the 


DIRECTION    OF   VEGETABLE    GROWTH.  375 

weight  of  the  liquid  in  the  cells  above  them.  In  other 
words,  they  are  subject  not  only  to  the  equal  hydraulic 
pressure  originating  in  the  roots,  but  also  to  a  slight  hy 
drostatic  pressure  from  the  overlying  cells.  This  pro 
duces  the  greater  extension  of  the  lower  passive  tissues, 
and  accounts  for  the  curvature  upward.  When  the  stem 
becomes  vertical  the  hydrostatic  pressure  is  equal  on  both 
sides  of  the  stem,  and  the  latter  is  accordingly  maintained 
in  that  position.  (Hofmeister,  Sachs.) 

Effect  Of  Light. — Besides  the  influence  of  gravitation 
and  of  interior  tension,  that  of  the  solar  light  must  be  re 
garded,  as  it  assists  largely  in  producing  the  more  com 
plex  phenomena  of  direction  in  the  growth  of  plants. 
The  explanations  already  given  refer  to  the  plant  when 
unaffected  by  light.  As  is  well  known,  the  stems,  leaves 
and  roots  of  plants,  when  growing  where  they  are  un 
equally  illuminated,  as  in  a  window,  in  most  cases  curve  or 
turn  towards  the  light.  More  rarely  is  curvature  away 
from  the  light  observed,  as  in  case  of  the  stems  of  ivy, 
(Hedera  helix),  and  the  young  rootlets  of  the  mistletoe, 
(  Viscum  alburn}.  The  common  nasturtium,  (Tropceolum 
majus),  exhibits  in  its  young  stems  inclination  towards, 
in  its  older  stems  inclination  away  from,  the  light.  Ita 
leaves  turn  always  towards,  its  roots  growing  in  watei 
often  curve  towards,  often  away  from  the  light. 


APPENDIX. 

TABLE  L 


COMPOSITION  OF  THE  ASH  OP  AGRICULTURAL  PLANTS  AND    PRODUCTS 

giving  the  Average  of  all  trustworthy  Analyses  published  up  to 
August,  1865,  by  Professor  EMIL  WOLFF,  of  the  Royal  Academy  of 
Agriculture,  at  Hohenheim,  Wirtemberg.* 


Substance. 


I.— MEADOW  HAY  AND  GRASSES. 


II  Meadow  hay 

2\ Young  grass 

8  Dead  ripe  hay 

4JRye  grass  in  flower 

5  Timothy 

6!  Other  sweet  grasses 

7iOats,  heading  out 

8|     "     in  flower 

9j Barley,  heading  out 

lOi  "  in  flower 

11  j  Winter  wheat,  heading  out 
12!  "  "  'in  flower... 

13  Winter  Rye,  heading  out. . 

14: Green  Cereals,  light 

15  "  "  heavy 

^Hungarian  millet,  green, 
I  (Panicum  gei-m.) 


13 

7.78;25.6    7.0 

4.9 

11.61  6.2!  5.T29.6!  8.0 

1 

9.  32  5(5.  2'  1.8 

2.8 

10.710.51  4.010.3 

2.0 

1 

7.73-  7.8    2.9 

3.4 

12.9 

4.4    0.763.1 

5.7 

4 

7.1024.9    4.2 

2.1 

7.5    7.8!  3.8.39.6 

5.4 

3 

7.01  28.8 

2.7 

3.7 

8.  4110.  81  3.9'35.6 

5.0 

39 

7.  27  as.  o 

1.8 

2.6 

5.5    7.8!  4.437.6 

4.1 

6 

7 

9.4641.71  4.4 
7.2339.0    3.3 

3.5    7.0J  8.3 
3.2!  6.71  8.3 

3.4  27.9 
2.733.2 

4.4 
4.0 

5 

8.93  38.5 

1.7 

2.9 

7.010.1 

2.931.2 

5.6 

5 

7.0420.2    0.6 

3.1 

6.0    9.8!  2.948.0 

3.5 

2. 

9.7384.7   1.9 

1.5 

4.9 

7.4!  2.841.9 

5.3 

3 

(5.9!)  25.7    0.5 

2.2 

3.1 

7.3    1.956.8 

2.8 

1 

5.4-2  88.6   0.3 

3.1 

7.414.7 

1.632.0 

6 

7.2029.6!  1.5 

3.9    6.6 

9.1 

4.1,41.4 

4!3 

5 

9.21  35.6 

3.4 

4.7   8.3 

8.1 

4.830  0 

5.6 

2 

7.2337.4 

8.0W.8   5.4   3.629.1 

6.4 

II.— CLOVER  AND  FODDER  PLANTS. 


56 

6.72134.5 

1  1.6112.  3134.0 

9.9 

3.0|  2.7 

3.7 

15 

6.0li20.# 

'1.9 

18.2!39.7 

9.4 

3.8 

l.fc 

5.4 

23 

0.74  29.8 

1.0 

11.8,35.6 

10.6 

3.0 

2.7 

2.9 

18 

7.1940.3 

1.4 

7.8127.3 

9  9 

2.2 

2.5 

3.2 

2 

7.1017.5 

7.8 

io.o:;->.-2 

1U 

8.8;  4.6 

3.2 

7 

7.1  1  25.3    1.1 

5.8;48.()    8.5 

0.1 

2.0 

1.9 

2 

6.8989.4   1.7 

5.  s  :52.  2  10.  4 

3.3 

4  0 

3.0 

2 

5.5888.8   1.5 

15.331.9  10.1 

4.01  1.2 

2.8 

1 

5.6010.8   4.5 

4.008.9 

7.0    1.6 

7.9 

o.a 

2 

S.  71  -1-2.1    -2.9 

6.820.3 

12.8    3.T 

1.8 

3.1 

1 

7.  40  40.  H    0.2 

8.228.7il3.2    3.5 

2.6 

1.8 

5 

8.97  32.3;  3.8 

4.523.1!  8.710.3 

3.2 

7.6 

17  Red  clover 

a.  15-25  percent  potash 

6.25-35        "  "        .... 

c.  35-50        "  "        .   ... 

18  White  clover 

19  Lucern 

20  Esparsette 

21  Swedish  clover 

22  A  nthyllix  vainer  aria 

23  Green  Vetches 

24  Green  pea,  in  t'.ower 

25  Green  rape,  young 


*  From  Prof  Wolff" s  Mittlere  Znxammensetz'ung  der  Asche,  oiler  land-  und 
forstwiriJixclutftlirfien  wic.htigen  Sfoffe,  Stuttgart,  1895.  The  above  Table  being 
more  complete  and  in  most  particulars  more  exact  than  the  author's  means  of 
reference  enable  him  to  construct,  and  being  moreover  likely  to  be  the  basis  of 
calculations  by  agricultural  chemists  abroad  for  some  years  to  come,  has  been 
reproduced  here  literally.  The  references  and  important  explanations  accom 
panying  the  original,  want  of  space  precludes  quoting.  In  the  table,  oxide  of 
iron,  aii  ingredient  normally  present  to  the  extent  of  loss  than  o:ic  per  cent,  is 
omitted.  Chlorine  is  often  omitted,  not  because  absent  from  the  pJ-tr.t,  but  from 
uncertainty  as  to  its  amount.  Carbonic  acid  is  also  excluded  iu  a>*  u*ses  f  >r  the 
uke  of  uniformity  and  tanlil.y  of  comparison. 

376 


APPENDIX. 


377 


COMPOSITION  OF  THE  ASH  OF  AGRICULTURAL  PLANTS  Atn>  PRODUCTS. 


Substance. 


g* 


in.— ROOT  CROPS. 


3.7459.8    1.6 


6.1665.4 

6.8653.1 


14.8 


4. 35  49.4    9.6 

8.2839.311.4 


7. -20  50. (i 
7.68!51.2 
(5.27136.7 


8.8 

6.7 
22.1 


4.51  2.319.1 


2.7    3.5116.0 


4  6   9.6 
6.314.; 


26Totatoes 

27  Artichokes... 

28  Beets 

29  Sugar  beets 

SO1  Turnips 

SljTurnips* 

32|Ruta-bagas 

33|Carrots 

34  Chicory 

85!Sugar  btet-headst 

IV.— LEAVES  AND  STEMS  OF  ROOT  CROPS. 

3  |  8.9214.5!  2.Ti16.8'39.0    (i.l 
1     5.12    6.3    0.822.646.2   5.5 


6.6!  2.3 


4.7 


2  8 
24 


10.413.814.8 

13.4  17.4!  6.0 

9.715  31  8.4 


5.21!40.4    7.7 


5.310.71-2.5 
6.3i  8.714.5 


2.f 

2.41  4  1 
1  Ij  6 


36  Potatoes,  August. 

37  "        October 

38  Beets 

39  Sugar  beets 

40!  Turnips 

41!Kohl-rabi 

42  Carrots 

43:Chicory 

44jCabbage 

45, Cabbage  stalk 


15.9629.1  21.0 
17.4922.1  16.8 
,13.6822.9  7.8 
16.8714.4  ::.!) 
13.57  14.1  23.1 
12.4660.0  0.7 
10.81  48.6  3.9 
6.4643.91  5.5 


9.7;11.4i  5.1 

4!532.'4  8!n 
4.033.310.4 
4.633.0,  4.7 
3.2  14.3:  9.0 
3.315.315.8 


4.S 


5.8 
5.5 

7.  ! 
8.0 
0.9 

LI. 7., 
7.9| 


8.5    1.2 


:!.! 
3.8 
10.5 


5.1 
3.2 
3.7 
0.5 


4.6 
3.0 


4.811.3 


4.1111.320.917  81 
V.— REFUSE  AND  MANUFACTURED  PRODUCTS. 


1.1 


4fijSugar  beet  cake 

a.  Common  cake 

\b.  Residue  of  maceration 

Ic.  Residue  from  Centrifugal 
machine 

47  Beet  molasses 

48  Molasses  slump  $ 

49  Raw  beet  sugar 

60  Potato  slum p^ 

51 1  Potato  fiber  !] 

52  Potato  juice  ^ 

53  Potato  Skills  § 

54  Fine  wheat  flour.  •. 

55  Rye  flour 

56  Barley  flour 

67  Barley  dust  ** 

58  Mai ze  meal 

59  Millet  meal 
BOlBuckwheat  grits 
01  Wheat  bran". 

6-2  Rye  bran 

(53  Brewer's  grains 

64  Malt 

65  Malt  sprouts 
66! Wine  grounds 
67!Grape  skins 

68  Beer 

69  Grape  must 
70jRape  cake 


3.15(36.61  8.4 
3.0825.012.7 
3.5385.3  "  A 


3.11 


45.5 


11.2871.1  10.5 
19.02|  89.8 

1.4383.8(28.0 
11. 10146.31  6.6 

0.9915.6 


5.6 


25. 3. 10.21  3.9!  6.2 
27.2pJ.9l  5. 


25V  13.0 

0.4    3  tf.  0.5 

o.a      o.i 
...I  <r.e  .... 

420.0 


8  ?,  -j  420.0  7.3 
7  »,•  J'.H  23.91.... 
.'.  ;\  J  .016.31  3.6 


•>.:'> 
6.5 

•2.1 
1.7 

0.9 
7.3!  3.4 

3.1 


1.5972.0    0.7 


1  •; 


0.47,86.0   0.9 

1.D738.4    1.8.  N  0 
33J28.81  2J   ;3.5 


5.6218.9 
. ...  28. 
1.35  19.7 
0.7225.4 
6.43  24.0 
8.2227.0 
5.17  4. 
2.7817.3 
6.5634.9 
4. 60 153.4 
4.04149.4 

87.5 

62.8 

6.59|24.; 


7.7 
3  0:14.9 
2  3  xJ5.8 
ff  912.9 


'«).(>  3.4 
2. S  5-2.0 
1.048.3 
2.847.3 
2.528.9 
6.3!45.0 


0.4 


0.710.1 
1.6 
5.8 
2.1 
1.3 


3  1 
.'.  20.0  .:.. 


147.3   2.7 
148.1    1.7 

(.6:16.8    4.7151.8  ...      1.1 

1.315.8!  3.5147.91 

0.810.111.688.0    0.832.2 
8.4    3.836.5  ....  33.2 


0.5 


1.4    1.521.0    6.329.5 


8.215.515.5   7.8 


13.020.8   4.4 

2.232.71.... 


0.9    5.6    4.9J17.7    6.5 
O.lill.5ll0.9i36.9    3.3 


5.7 
8.2 
3.9 
7.1 
1.7 
2.5 
1.9 


4.8 
13.0 
0.9 


7.5 
2.1 


1.6 


0.5 
0.6 


3.5 

10.2!     .. 

1.3    0.6 

8.7:  0.2 


*  White  turnips  in  the  original,  but  apparently  no  special  kind,    t  Probably 
the  crowns  of  the  roots,  removed  in  sugar-making.    $  The  residue  after  ferment- 


Ing  and  distilling  off  the  spirit.     ||  Refuse  ot  starch  manufacture. 
$  Prom  boiled  potatoes.    **  . 


"*  Refuse  in  making  barley  grits. 


Undiluted. 


378 


HOW    CROPS   GROW. 


COMPOSITION  OF  THE  ASH  OP  AGRICULTURAL  PLANTS  AND  r 


Subsidise. 


V.— REFUSE  AND  MANUFACTURED  PRODUCTS. 


71  Linseed  cake 

72  Poppy  cake 

73  Walnut  cake 

74  Cotton  seed  cake. 


6.24123.3 
10.6020.8 
5.3633.1 
6.95;35.4 


1  1 
4.6 

15.9 
4.3 
12.2 
4  3 

8.6135.21 
28.1  37.8 
6.743.8 
4.648.3 

3.4 

2.0 
1.2 
1  1 

6.5 
4.8 
1.6 
4  0 

0.1 


75  Winter  wheat. 

76  Winter  rye.... 
77|Winter  spelt. . 
7-S  Summer  rye.., 

79  Barley 

SO  Oats 

81  Maize 

82'Peas  

83;Field  bean.... 
84  Garden  bean.. 
85:  Buckwheat.... 

86'Rape 

87|Poppy 


VI.— STRAW. 
12 


4.9611.5    2.9    2.6 

6.2    5.4 

2.9!66.3 

4.81  18.7   3.3 

3.1 

7.7 

4.7 

1.958.1 

5.5611.2!  0.4 

0.9 

4.8 

6.3 

1.871.4 

5.5523.41   ... 

2.8 

8.9 

6.5 

2.655.9 

5.1021.6    4.5 

2.4 

7.6 

4.3 

8.753.8 

5.1222.0    5.3 

4.0 

8.2 

4.2 

3.5 

48.7 

5.4935.3 

1.2 

5.5 

10.5 

8.1 

5.2 

38.0 

5.7421.81  5.3 

7.737.9 

7.8 

5.6 

5.7 

6.1 

7.1244.4 

3.8 

7.8 

23.1 

7.0 

0.2 

5.4 

13.8 

6.0637.1 

6.0    5.2:27.4 

7.8 

3.6 

4.7 

5.2 

6.1546.6 

2.2    3.6 

18.4 

11.9 

5.3 

5.5 

7.7 

4.5826.6110.81  5.7 

26.5    7.0 

7.1 

6.7 

12.4 

7.8638.0    1.31  6.5;30.2|  3.5 

5.1 

11.4 

2.5 

VII.— CHAFF,  ETC. 


RSlWheat 

m  Spelt 

fOJBarley 

UOata 

^2 [Maize  cobs 


1  14.23    7.7  0.9    1.310.4 

1  9.2213.1  4.8    2.6,  8.9 

1  0.5647.1  1.2i  4.1    3.4 

#iFlax  seed  hulls ...        1  6.6231.1  4.3    2. 8J29. 6 


10.73 
9.50 

14.23 
9.22  13.1 
0.5647.1 


1.81  1.3!  1.9!  4.3 

0.3i 

0.9 

4.8 

1.9 


2.5!  2.41  7.3    2. 

•I      O-IA     A\      C\     ni      O 


374. 


2.0  3.070.8 

0.3  2.5 

4.41  1 

2.8J  4. 


L.920 
817. 


59.9 

.4 


0.1 


VIII.— TEXTILE  PLANTS,  ETC. 


94  Flax  Straw 

95  Rotted  flax  stems. . 

96  Flax  fiber 

97  Entire  flax  plant... 

98  Entire  hemp  plant.. 
""  itire  hop  plant... 

Hops 

Tobacco 


9!)  E 


102lHeath 

103 !  Broom  (Spartium) 

104!  Fern  (Aspidium) 

Kd  S.-ouriiiLr  rush  (Equisetum)... 

10(1  S.'a-weed(.tfwcMS) 

107  I'.''<'rh  lta\es  ii_  autumn 

lOsOak          "        " 

1  ( )< t  F i  r  "    (Pinns  gyfatftrit} 

110  KVd  pine  leaves  (Pinus  Picea) 

111  K'crd  (Arundophrag.). . .  (_ria} 
1U  l)mvn  eraM  (I'.vimina  area- 

118  Sedge  (potto;) 

lit  Rush  (Junctu) 

115. Bulrush  (jSdrpus) 


IX.- 
8 
2 

2 

S 


3.71136.9 
2.401  9.0 
0.67|  3.3 
4.3034.2 
4.60118.3 
9.8726.2 
6.8037.3 
24.08127.4 


5.1 

7.1 

22.3 

11.5 

*!a 

8.9 

5.4 
5.4 

51.4 
03.6 

5.9 
10.8 

4.8 

9.0 

15.5 

23.0 

8.2 

9.6 

43.4 

11.6 

3.8 

5.8 

16.0 

12.1 

2.2    5.5 

10.9 

15.1 

3.7]10.5|37.0 

3.6 

5.8 

2.  '7 

4.9 

8.8 
5.4 
8.6 
8.9 

6.0 
13.8 
6.2 
2.0 
7.6 
21.5 
15.4 
9.6 

4.0 

'6.4 
5.9 
2.5 
4.6 
3.4 
4.5 

-LITTER. 

4.51!13.2 

5.31  8.4 

18.8 

5.1 

4  ,)  ;y,  o 

2.1 

2.25  36.5 

2.5 

12.4 

17.1 

8.6 

3.'5 

10.3 

2.7 

IM  4->!s 

4.5 

7.7 

14.0 

9.7 

5.1 

6.1 

10.2 

23.  77  13.2 

0.5 

2.312.5 

2.0 

6.353.8 

5.7 

14.3914.5 
6.75    5.9 

24.0    9.5|l3.9 
0.6    6.041.9 

3.1 
4.2 

24.0 
3.7 

1.7 
88.9 

10.1 
0.4 

4.90    3.5 

0.6 

4.0148.6 

8.1 

4.4 

30.9 

9.9141.4 

16.4 

4.4 

13.1 

'4"4 

r>>2   i>i 

2.3 

1.-..2 

8.2 

2.s 

70.1 

4.01t    S.O 

'6'2 

1.2 

5.9 

2.0 

2.S 

71.5 

.... 

....   |29.8 

4.0 

3.8 

16.5 

7.2 

3.6 

18.5 

8.  08  33.  2 
5.8086.6 

7.:; 

«;.«; 

10.3 

4.2 
6.4 
3.0 

5.3 
7/2 

6.7 
6.4 
6.5 

3.3:31.5 
8.710.9 
5.6143.3 

'5.6 

14.2 

X.— GRAINS  AND  SEEDS  OF  AGRICULTURAL  PLANTS. 


116  Wheat 

117  Rye..., 

118  Barley. 

1 19  Oat«  . . 


2.07 


3.512.2 
1.810.9 


2.5521.9    2.8 
3.07  15  9    3.8 


40.2 
47.5 


2.5  32.8 


2.41 
2.3 


APPENDIX. 


379 


OF   THE   ASH  OF  AGRICULTURAL  PLANTS  AND   PRODUCTS. 


Substance. 


X.— GRAINS  AND  SEEDS  OF  AGRICULTURAL  PLANTS, 


120  Spelt  with  husk.. 

121'Maize 

122  Rice  with  husk... 
123 !    "    husked 

124  Millet  with  husk. 

125  "      husked 

126  Sorghum 

127,Buckwheat 

12SRapc       seed 

129  Flax  "      .... 

130  TIemp        "      

131  Poppy        "      .... 

132  Madia        "      .... 

133  Mustard    "      ... 

134  Beet  " 

135  Turnip      "      

13(5  Carrot        "      

137  Peas...; 

138  Vetches 

13'.)  Field  Beans 

140, Garden  beans 

141 'Lentils 

142  Lupines 

143  Clover  seed 

144jEsparsette  seed. . . 


4.2017.3J  1.8|  5.8 
1.514.6 
4.5 


7.84,18.4 
0.39123.3 
4.49J11.9 
1.42118.9 
1.8020.8 
1.0712,3.1 
4.24  23.5 
3.6532.2 
5.4820.1 
6. 1213.  6 


8.6 
4.813.4 

1.0  8.4 
5.818.6 
3.314. 
6.213.4J  3 

1.1  12.213 
1.818.8   8 
0.8J  5.6  23 
1.1)    9.535 


....  9.511.215.4,  7 
4.30.15.9  5.810.218 
5.6818.717.818.9:15 

3.98:21.9!  1.2|  8.717 
8.50:19.1    4.8]  6.7,38 
2.81140.4)  3.7 
2.40,30.610.6 


3.45  40.5 
3.0644.1 
2.0627.8 


1.8 


5.2    7 


....133.517.8  _._,  . 
4.1137.31  0.612.2  6 
4.4728.6!  2.8  6.6131. 


8.0   4 

8.5    4 
6.7 
7.5 
8.0 


.6120.0 
.744.7 
.147.2 
.951.0 
.023.4 
.  53.6 
.350.9 
.348.0! 
.843.9; 
.440.4! 
.536.3! 
.431.4: 
.755.0! 
.8,39.0 

.615.5: 

.440.21 

.8,15.81 
.236.3 

.8:38.1 

.239.2 
.730.4! 
.1  29.1! 
.825.5 
.233.5 
623.9 


.644 


3.2 

0.6 
0.6  30 
0.252.3 
1.5 

7.5 
2.1 
3.6 
1.1 


1.1 
1.1 


1.7 
0.3 
0.1 


0.2,11.* 
1.9!  3.2;  4.4 


4.7    2.4>  0.4 

4.2 

7.1 

5.6 

3.5 

4.1 

5.1 

3.8 


6.8 
4.7 
8.8 


2.11  9.4 
0*7..*. 
6.8  3.3 
0.9  2.3 
2.0  1.1 
1.2  2.9 


XI.— FRUITS  AND  SEEDS  OF  TREES,  ETC. 


145jGrape  seeds 

146  Alder 

147i  White  pine 

148!Redpine 

149  Beech  nuts 

150  Acorns 

151  Horse-chestnut 

152!  "  green  husk. . 

153  Apple,  entire  fruit 

154  Pear,         "       "     

155  Cherry,      "        "     

150  Plum,        "        "     


2.81 
5.1437.61  1.6 


21.8 
22.4 


7.1 


8.633.924.0    2.5    1.1! 
8.030.713.0    3.4!  3.2 


16. 


1.315.1 


1.539.71. 
1.946.01. 


3.30  22.8  10.0ill.6  24.5  20.8 


64.5j  0.7 
2. 36J5S. 9J.... 
76.4'.... 
35.7J26.1 

54.7    8.5 
51.9;  2.2 


5.41  7.0  16.2 
0.511.638.4 

1.010.01  6.3 
4.1  13.6 


5.8 

5.5 


8.015.3 
7.516.0 


..159.2!  0.5|  5.510.015.1 
XII.— LEAVES  OF  TREES. 


.   .111.7 
...10.4 

2.2  l.U, 
2.8  1.1 
1.4  0.2i 
1.4  0.6| 
6.1  4.31 
5.7!  1.5  . 
5.1!  9.0 
8.8i  2.4!. 


0.9 
3.3 
1.8 
1.3 
1.1 


0.3 
0.1 
0.3 


1.7 
6.4 
5.6 


157  Mulberry 

158j  Horse-chestnut,  spring 

159)  autumn 

160  Walnut,  spring 

161  "       autmii  -. 

162  Beech,  summer 

163;       "      autumn 

It)4  Oak,  summer 

165'     "    autumn 

166  FIT  autumn 

167, Rea  pine,  autumn 


3.53:19.6 
7.1738.8 
7.5219.6 
7.7242.7 
7.01  26.6 
4.83118.5 
6.75  5.2 
4.6033.1 
4.90  3.5 
1.4010.1 
5.82  1.5 


5.4|2B.7|10.2|  0.5 

33.5 

.... 

3.921.323.4 

6.0 

2.9 

7.840.5 

8.2 

1.713.9 

4.626.9 

21.1 

2.6 

1.2 

9.8;53.7 

4.0 

2.7 

2.0 

'i'.s 

8.636.5 

7.8 

3.1 

15.2 

0.6 

6.0 

44.9 

4.2 

3.7 

33.9 

.... 

13.5 

26.1 

12.2 

2.7 

4.4 

0.6 

4.0 

48.6 

8.1 

4.4 

30.9 

9.9 

41.4116.4 

4.4 

13.1 



2.315.21  8.2 

8.8170.1 

xni.— WOOD. 


168:Grape I  8 

16!)  Mulberry 1 

170  Birch I  2 

171  |Beech,  body-wood |  2 


2. 75,29. Si  6.7;  6.8137.312.91  2.7 
1.60|  6.514.8]  5.757.3  2.210.3 
0.31  11.6  5.8  8.9J60.0  8.5  0.3 
0.6516.1  3.410.8156.41  5.3  1.0 


0.1 
3.8 
4  1 
0.5 
0.8 
1.2 
0.4 
0.1 

4.4 


0.8 
4.2 
0.6 
0.1 


380 


HOW   CROPS    GROW. 


COMPOSITION  OF  THE  ASH  OP  AGRICULTURAL  PLANTS 


PRODUCT*. 


Substance. 


P 
* 


XIII.— WOOD. 


ITS 

17:', 
171 
175 
17<» 
177 
17s 
17!) 
180 
Iffl 

is:! 
184 

1S5 
isi; 
its; 

186 

1>9 
190 
191 
192 

I'.):; 
19-1 
105 
U* 

Beech,  small  wood  

1 
1 
2 

1.05 
1.45 

a!  si 

2.99 

15.2 
14.1 
10.0 

19.8 
19.4 
15.:! 
14.0 
11.4 
0  1  1 

2  1 

sis 

3.6 

'6i4 

5.6 
0  1 

16.845.8 
10.848.0 
4.873.5 
7.554.0 
5.251.0 
8.155.9 
7.5  58.4 
10.1  50  8 
10  0  37  9 

11.6 
12.3 
5.5 
9.3 
21.7 
12.2 
13.1 
16.4 
9  fi 

0.7 
1.2 
1.4 
1.6 

lie 

3.1 
5.4 
1.3 
5.3 
2.9 
3.0 
3.0 
2.3 
1.7 

1.3 
1  3 

(5.7 
9.8 
1.1 
3.1 
0.7 
2.9 
2.0 
0.7 
62 
3.1 
5.3 
1.8 
2.0 
6.0 
15.0 
3.6 

20.1 
18  0 

0.1 
0.1 
0.2 

ois 

0.1 
0.6 
6.7 

0^2 
4.0 
0.2 
0.4 
0.6 

1.3 

41      brush 

Oak,  body-wood  [bark 
44     small  branches  with 
Horse-chestnut  twigs,  autu'n 
Walnut  twigs,  autumn  
Poplar,  youn°p  twi^s     

Willow       "          4' 

Elm,           "          "    

1 

Elm   body-wood 

21.9 
85.8 

12.0 
5.2 
15.3 
11.8 
15.3 

RK. 

3.8 
14  7 

13.7 
6.0 
1.6 

2«5.8 
9.9 

4.G 

7.7 

5.4 
0  4 

7.747.8 
4.2129.9 
5.771.0 
6.247.9 
6.950.1 
9.1  50.1 
24  5  27.1 

S.2'46.6 

0.257.9 

3.3 
4.9 
4.6 
5.1 
5.5 
5.8 
3.6 

7.3 
0  4 

Linden  

1 

Apple  tree.           

2 
1 
2 
6 
1 

XIV 

2 
1 

1.29 
0.25 
0.28 
0.31 
0.32 

—  BA 
1.33 

Red  pine  

White  pine..  . 

Fir 

Larch  

Birch 

Beech  

Horse-chestnut,  young,  aut'n 
Walnut,                   "          " 
Elm 

1 
1 
1 

6.57 
6.40 

24.2 
11.15 
2.2 
16.1 
5  3 

io'.i 

5.7 
4  /J 

4.061.3 
10.670.1 
3.2:72.7 
8.0'60.8 
4.7:62.4 

7.0 
5.9 
1.6 
4.0 
2.6 
2.5 
8.3 

1.1 
0  2 
0.6 
0.8 
1.0 
1.6 
0.8 

1.1 
0.7 
8.9 
2.3 
15.7 
8.4 
81.1 

1.2 
0.4 

"i  a 

o  a 

1  0 
i  7 

Linden 

1 

Red  pine  

1 

9,  81 

White  pine 

1 
8 

3.30 
2.01 

8.0 
3.0 

3.2 
1.0 

3.009.8 
1.4|43.7 

Fir... 

APPENDIX. 


38] 


TABLE    II. 


CCSTrOSITTON  OP  FRESH  OR  AlR-DRY  AGRUCTLTURAL  P  iODUCTS,  giving 

tlie  average  quantity  of  Water,  Sulphur,  Ash,  and  Ash  ingredients, 
in  1,000  parts  of  substance,  b}T  Prof.  WOLFF. 


Substance. 


I.— HAY. 


Meadow  hay.... 
Dead  ripe  hay.. 

Red  clover 

White  clover. . 
Swedish  clover. 

Lucern 

Esparsette 

Green  vetches.. 
Green  oats 


1441  60.617.11  4.71  3.3|  7.7    4.1 
144   66.  2j  5.0l  1.9;  2.3i  8.61  2.9 

3.419.7!  5.31.7 

0.5i41.8|  3.8|2.7 

160    56.5  19.  5i  0.9 

6.919.2    5.6 

1.7 

1.5 

2.1;2.1 

100 

60.310.6    4.7 

(5.019.4    8.5 

5.3 

2.7 

1.92.7 

160 

46.515.7    0.7 

7.1  14.8    4.7 

1.9 

0.6 

1.3  ... 

160 

60.015.2    0.7!  3.528.8!  5.1 

3.7 

1.2 

i.ija.6 

If  id 

45.317.9;  0.8 

2.6  14.6    4.7 

1.5 

1.8 

1.4i... 

160 

73  4  30  9    2  1 

5  0  19  3    94 

o  7 

1   3 

9  31.5 

1!.-, 

61.  8J24.  1|  2.0 

2.0,  4.1    5.1 

1.7 

20.5 

2.5,1.5 

|800i  20.7S11.6!  0.4|  0.6> 
17001  21.31  5.3    0.9;  0.5 


Rye  fodder 700 

Hungarian  Millet 680 

Red  clover 800 

White  clover 810 

Swedish  clover 815 

Lncern 753 

Esparsette , 785 

780 
820 

peas 815 

rape., 1850 


Anthyllis  vulneraria. 
Green  vetches . . . 


H.— GREEN  FODDER. 
Meadow  grass,  in  blossom....  !700 1  23.3!  6.0    1.6    l.l! 

Yonng  grass 

Rye  erass 

Timothy 

Other  grasses 

Oats,  beginning  to  head 

"     in  blossom 1770 

Barley  beginning  to  head 750 

"      in  blossom 1680 

Wheat,  beginning  to  head....  770 

"       in  blossom . .  690 


21. 0|  6.1 
21.81  7.2 
17.0  7.1 


0.4   0.6 
0.8   0.6 


16.6;  6.5  0.6  0.5 

22.31  8.6  0.4J  0.7 

22.5    5.9J  0.1:  0.7 

22.4    7.8  0.4i  0.3 


16.3 
23.1 


13.4 


5.6]  0.1]  0.5 
6.3|  O.lj  0.5 
8.6 


1.9 
„._.  4.6J  0.2|  1.6 

13.6    2.4|  1.1    1.4 
10.2    3.5|  0.2    1.6 


17.6 
11.6 
12.3 


4.5 
4.6 


16.7   6 


13.71  5.6l.!.|  1. 
I  4.41  0.51  0. 


0.2  1.0 
0.2;  0.7 
0.5|  0.6 
0.5  1.1 
.1 


18.61 


2.71  1.5' 
2.2:  2.2| 
1.6  1.7 
2.0  2.3 


1.2  6.9! 

O.S|  2.11 

0.8  8.4 

0.8  7.5! 


1.7 
1.4J 
1.4 
2.3 
2.2' 
1.7 
1.6 
2.4 
1.8 
1.:; 
2.0 
l.n 
1.5 

i.a 


1.0  8.2 
0.6  4.71 
0.5  6.61 
0.7  7.0 
0.7I10.8| 
0.4J  9.4 
0.4:12.3 
0.2;  5.2 
0.8  6.7 
0.4|  0.4 
1.2  0.6 
0.4  0.1 


8.5  0.9| 

4.1  2.0 

3.9  1.8 

8.1  1.2i 


HI.— ROOT  CROPS. 


Potato 

Artichoke 

Beet 

Sugar  tyeet 

Turnip 

White  tnmir  * 

Kohl-rabi 

Carrot 

Sugar  beet-heads  t. 
Chicory 


|750      9.4 
800'  10.3 


ss:5 
816 
909 

915| 


840, 


8.0 
8.0 
7.5 
0.1 
9.5 
8  - 
6.6 


800i   10.4 


5.6    0.1 
.7  .   .. 
4.3    1.2 
0.8 


0.4 
0.8 

0.4 
0.7J 
0.3 
O.li 


0.2    1.8    0.6    0.2 
"       J       0.8. ... 
0.3    0.2 
0.41  0.3 


1.6! 

0.8! 

1.1 


l.Ol 


0.8    1.1 

«.»,  .,.«  0.9    1.4 
1.9!  0.5!  0.9 


1.6 

0.8l 


1  1, 
0  8^ 
1.61 


0.2 

0.1 
0.8|  0.1 
0.6|  0.2 
0  51  0  1 
1.0!  0.6 


1.9:0.6 
0.40.4 
1.1  0.7 
1.10.8 
0.90.7 
0.810.3 
0.7J0.4 
1.210.5 
0.8!0.7 
1.20.3 
0.60.5 


0.50.6 
0.410.6 
0.3  ... 
0.30.8 
0  3 

6'.50.3 

o.a... 

1.00.6 


0.3:0.2 

0.2  ... 

0  50.1 

0.2!... 

0.3,0.4 

0.4|... 

0.5J... 

0.310.1 

O.ll.. 

0.4l   . 


*  No  special  variety?    t  C'rowus  of  sugar  beet  r  ota. 


362 


HOW   CROPS   GROW. 


COMPOSITION  OF  FRESH  OB  AIR  DRY  AGRICULTURAL  PRODUCTS 


Substance. 

k 
3 

— 

T-H 

| 

1 

Magnesia. 

1 

I            t  ^ 

I 

j 

j 

IV.—  LEAVES 
Potato  tops,  end  of  August.  .  . 
"         "     first  of  October.. 
Beet  tops 

A* 
825 
770 

907 
Mt7 
Mis 
s:,o 
S;)S 

s'';, 
820 

ui; 

692 
692 
S20 
SS.1 
175 
907 
43 
917 
S(H5 

:;oo 
186 
112 
140 
118 
liu 
no 
140 
1.-J5 
l:;l 
768 
•175 
.(•> 

'D  SI 
15.6 
11.8 
14.8 
18.0 
14.0 
25.3 
26.1 
18.7 
12.4 
11.6 
ED  P 
9.7 
9.3 
5.6 
4.1 
93.1 
17.7 
13.7 
5.9 
1.9 
67.1 
4.1 
10.9 
20.0 
49.8 
9.5 
11.6 
6.2 
55.6 
71.4 
12.0 
14.6 
26  6 

EMS 
2.3 
0.7 
4.3 
4.0 
3.2 
3.6 
3.7 
11.2 
6.0 
5.1 
ROE 
3.6 
2.3 
2.0 
1.5 
06.  2 
15 
4.6 
2.7 
0.3 
48.3 
1.5 
6.5 
5.8 
9.4 
2.7 
2.3 

i!e 

13.3 
19.3 
0.5 
2.5 
.1   0 

>  OF 
0.4 
0.1 
3.1 
3.0 
1.1 
1.0 
6.0 
0.1 
0.5 
0.6 
UC1 
0.8 
1.2 
0.5 
0.4 
9.8 
9 
3.8 
0.4 

ois 

0.1 
0.3 
0.5 
0.7 
0.3 
0.3 
0.4 
0.3 
0.9 
0.1 

RO 
2.6 
2.7 
1.4 

Oi6 
1.0 
1.2 
0.6 
0.4 
0.5 
S  A 
0.5 

OT  ( 

5.1 
5.5 
1.7 
3.6 
4.5 
8.4 
8.6 
2.7 
1.9 
1.3 
ND  1 
2.5 
2.5 
1  /I 

;ROI 

1.0 

o.r 

0.8 
1.3 
1.3 
2.6 
1.2 
1.7 
2.0 
2.4 
IEF1 
1.0 
1.2 
0  7 

0.9 
0.6 
1.1 
1.4 
i  1.4 
3.0 
2.1 
1.7 
1.1 
0.9 
JSE, 
0.4 
0.5 
0  -1 

1.2 
0.5 
0.7 

Oi5 
2.6 
1.5 
0.2 
0.1 
0.2 

0.6 

0.7 
0.4 
1.7 
1.0 
1.2 
1.0 
1.9 
0.3 
0.3 
0.1 

0.5 

1.2 

lO.'J 

iO  5 
,0.5 

6'.5 

iii 
°i5 

Sugar  beet  tops  

Turnip  tops 

Kohl-rabi  tops  

Carrot  tops  

Chicory  tops 

Cabbage  heads  

Cabbage  stems. 

V.—  MANUFAC1 

Su^ar  beet  cake 

a.  Common  cake.  .  .  .  [machine 
b.  Residue  from  Centrifugal 
c.  Residue  of  maceration  
Beet  molasses 

0.5    1.1 
0.4    5.6 
0  2 
...      1.2 
0.5    0.4 
0.1    0.9 
4.5    6.4 
0.3    0.1 
l.t    0.2 
2.7i  0.6 
3.8    1.2 
1.4    0.6 
3.0  .... 
0.8    0.1 
9.4    2.6 
11.3    2.5 
1.2,  1.4 
1.2    ()..-> 
2210 

0.3 
0.6 

ois 

2.3 
2.1 
8.5 
9.5 
14.4 
4.3 
5.5 
3.0 
98  i8 
34.2 
4.6 
5.3 
0  7 

0.1 
2.0 
0.3 
3.1 
0.4 

6i3 

0.6 

'o.i 

0.2 
0.1 
1.8 

0.1 
9.4 
0.3 

0.8 
0.1 

.... 
1.4 

iii 

Molasses  slump  *  

Raw  beet  su^ar. 

Potato  slump  * 

Potato  fiber  t  

Potato  skins  J 

Fine  wheat  flour  
Rye  flour 

...... 

Barley  flour  

Barley  dust  1  

9.9 

Maize  meal 

Millet  meal  
Buckwheat  """its 

0  3 

0.1 

'6'6 

0.1 

Wheat  bran  

Rye  bran                      .  . 

Brewer's  grains 

0.1 

3.9 

4.8 

R  8 

— 

..i 

Malt.               

Dried  malt 

Malt  sprouts  
Wine-<rrounds 

93 

(lJs.1 

900 
"SOO 
150 
115 
leu 
L86 
116 

1  1! 

1  !:'; 
143 
140 

111 
I  In 

59.620.8 
16.1    8.6 
16.2    8.0 
3.9    1.5 
2.8    1.8 
56.018.8 

.V,.  2  12.9 
95.  -1  19.  S 
46.  I  15.4 

til...  21.  S 
—STRA 
42.61  4.91 

10.7    7.0 
47.71  5.3 
17.0  11.1 
l;  9    9  :; 
41.0    9.7 
•17  2  10  0 

Oi4 
0.3 

ois 

4.3 

VV. 
1.2 
1.3 
0.2 

'2'.  6 

2.3 

0  r> 

0.8 
0.5 
1.0 
0.2 
0  2 
6.4 
8.8 
4.1 
5.7 
2.6 

1.1 

1.3 
0.4 
1.3 
1.1 

I  is 
2  6 

0.9 
2.5 
2.1 
0.1 
0.2 
6.1 
4.7 
20.8 
3.1 
2,8 

2.6 
8.1 
2.3 
4.4 
3.3 
3.6 
R  0 

12.5 
2.5 
3.4 
1.3 
0.5 
20.7 
P.I.  t 
30.1 
20.3 
29.5 

2.3 
1.9 
3.0 
3.1 
1.9 
1.8 
3  R 

3.8 
1  ° 

17.7 

0  1 

Grape  skins  

0.7 
0.1 
0.1 
1.9 
1.9 
1.9 
0.5 
0.7 

1.2 
0.8 
0.9 
1.2 

lis 

o  r, 

0.6 
0.4 
0.1 
4.9 
3.0 
4.6 
0.7 
2.5 

28.2 
23.7 
34.1 

20.0 
23.6 
21.2 
17  () 

0.1 
0.1 

... 

Beer  .        .            

Wine 

Rape  cake  

0.1 

0.3 

Linseed  cake.     .. 

Walnut  cake  
Cotton  seed  cake  

Winter  wheat    

....11.6 
....0.9 

Winter  rye 

Winter  spelt  

Summer  rve                         .    .  . 

Barley 



1.3 

1.7 
3.9 
0.1 
2  3 

ail 



Mai/c                                        .    ... 



143 
L80 
150 

49  2  10.7 
58.  1  25.9 

51.619.1 

2.6 
2.2 
3.1 

3.8 
4.6 
2.7 

18.6 
13.5 
14.1 

3.8 
4.1 
4.1 

2.8 
0.1 

1.8 

2.8 
3.1 
2.4 

3.0 

8.1 

2.7 

Fi  •!<]  bi-an                    ' 

Ciar.l;-ii  1>  an... 

*  K .-i'lni-  fn mi  spirit  manufacture      t  Refune  of  starch  manufacture 
boiled  potatoes.     J  Refuse  from  nuking  barley  grits. 


t  Frcno 


APPENDIX. 


383 


COMPOSITIDN  OF  FRESH  OB  AlR-DRT  AGRICULTURAL,  PRODUCTS. 


Substance. 

| 

j 

3 

i 

Magnesia. 

1 

4"S 

1H 
{! 

<i 

1* 

P 

| 

£ 

O 

! 

Buckwheat    

UK 

171 
Kit) 

188 

l.-J.) 

1  ID 

VI.—  ST1 
51.7124.1 
38.0    9.7 
66.0125.1 
VII.—  CE 
92.5    8.4 
82.7    7.9 
122  494 

*AW 
1.1 
3.9 
0.9 
[AFI 
1.7 
0.2 
1  1 

1.9 
2.1 
4.3 
\ 

1.2 
2.1 
1  6 

9  5 
10.1 
19.9 

1.9 
2.0 
1°  7 

6.1 
2.7 
2.3 

4.0 
6.0 
o  4 

2.7 
2.7 
3.4 

i!9 

3  7 

2.8 
2.6 
7.5 

75.1 

61.4 

86  7 

4.0 
4.7 
1.7 

ki 

0.8 

Kape 

Poppy  

Wheat 

Spelt       

Barley       

Oats 

14t! 
115 
1-21) 
—  '1 

140 
100 

10i  I 
860 

79.0 
5.0 
58.3 
EXT1 
31.9 
21.6 
6.0 
32  3 

1:t 

18.1 
UE 
11.8 
1.9 
0.2 
11.3 
5.2 
19.4 
•22.3 
54.1 
-LIT 
4.8 
6.9 
25.2 
27.0 
17.1 
3.0 
1  5 

3.8 
0.1 
2.5 
PLAI 
1.6 
1.0 
0.2 
1.5 
0.9 
2.8 
1.3 
7.3 
TER 
1.9 
0.5 
2.7 
1.0 
28.3 
0.3 
0  ° 

2.1 
0.2 
1.6 

<TTS, 
2  3 
1.2 
0.3 
2.9 
2.7 
4.3 
2.1 
20.7 

3.0 
2.8 
4.5 
4.7 
11.2 
3.4 
1  7 

7.0 
0.2 
17.2 
ETC 
8.3 
11.1 
3.8 
5.0 
12.2 
11.8 
10.1 
73.1 

6.8 
3.2 

8.3 
•25.  (i 
16.4 

•25.8 

•N)  '> 

0.2 
0.2 
1.6 

4.3 
1.3 
0.7 
7.4 
3.3 
9.0 
9.0 
7.1 

1.8 
1.6 
5.7 
4.1 
3.7 
2.4 
^  4 

2.0 
0.1 

2.8 

2.0 

0.7 
0.2 
1.6 

0.8 
3.8 
1.6 

7.7 

1.6 
0.7 
3.0 
12.9 

28.3 
2.1 
1  8 

47.3 
1.3 
10.0 

2.2 

3.0 
0.3 
0.8 
2.1 
15.9 
9.2 
19.0 

12.7 
1.9 
3.6 
110.0 
2.0 
19.5 
12  9 

Maize  cobs  

0.2 
3.6 

1.5 

1.3 
1.8 

1.4 

0.2 

Flax  seed  hulls    . 

VIII 
Fln.z  strav?  

Rotted  flax  stems.        . 

Flax  fiber  

Entire  flax  plant  

1.9 
0.7 
3.4 
0.2 

8.8 

0.8 
0.5 
6.0 
11.7 
11.9 
0.2 

'2'.6 
4.8 

Entire  hemp  plant  
Entire  hop  plant  

30') 
260 

tao 

180 

200 
100 
ItiU 
1-10 
IS!) 
1.7) 

1.50 
160 

1'iO 
1st) 

no 
140 

110 
Si 

143 
149 
146 

1  to 

IIS 

l.T, 
190 
i:;o 
i:;o 
131 
140 
Hi 
120 
IIS 
H-2 
117 
Hi 
1  10 
HO 
HO 
Us 
136 

28.2 
74.0 
59.8 
197.5 
IX.- 
36.1 
18.9 
58.9 
204.4 
118.0 
57.4 
41  7 

Hops 

Tobacco 

Heath                       .     . 

Broom  (Sparliurri)  

Fern  (Aspidium)  

Scouring  rush  (Equisetum)  .  . 
Sea-weed  (Pucus)  
Beech  leaves  

Oak  leaves 

Fir  leaves  (Pinm  sylvestris).. 
Red  pine  leaves  (Pinuspiced) 
Reed  (Arundo  phrag  ) 

11.8 
48.9 
38.5 
69.5 
45.6 
74.4 

;EDS 

17.7 
17.3 

21.8 

->(!    ! 

1.2 
0.7 
3.3 
23.  1 
16.7 
7.2 
OF 
5.5 
5.4 
•j.s 
4  2 

'6!i 

5.1 

3.0 
7.7 
A.GR 
0.6 
0.3 

o.i; 

1  0 

1.1 
1.1 
0.5 
2.9 
2.9 
2.2 
ICTJI 
2.2 
1.9 
1.8 
O 

4.9 
7.4 
2.3 
3.7 
4.3 
5.4 
.Till 
0.6 
0.5 
0.5 
1   0 

1.9 
4.0 
0.8 
4.7 
2.9 
4.8 
IAL 
8.2 
8.2 
7.  -2 

0.5 
1.4 
1.1 
2.3 
4.0 
4.2 
PLA 
0.4 
0.4 
0.5 
0,1 

o'n 

0.1 
0.4 

'6!i 

0.2 

'6!2 

1.3 

0.4 
0.1 
1.0 
1.8 
2.0 
2.5 
4.2 
0.8 
0.9 

1.5 
34.3 
27.5 
21.8 
5.0 
32.2 

:NTS. 

0.3 
0.3 
5.9 
12.3 

ir/s 

0.3 
0.4 
0.1 
20  5 

0.5 

Sed"-e  (Carex)  

3.9 
6.5 
3.9 

1.5 

1.7 
1.4 

1.7 

Y.9 

i'.a 

Rush  (Juncus)  
Bulrush  (Scirpus) 

X.—  GRAINS  AND 
Wheat       .           

Rye 

Barley 

Oats  • 

Spelt,  with  husk  

Maize 

SO 

12.3 

69.0 
3.4 

39.1 
12.3 
16.0 
9.2 
37.3 
32.2 
48.1 
52.2 
37.8 
48.7 
35.0 
74.8 
24.2 
20.7 

6.2 
3.3 
12.7 
0.8 
4.7 
2.3 
4.2 
?  1 
8.8 
10.4 
9.7 
7.1 
6.0 
9.1 
7.7 
14.3 
9.8 
6.3 

0.6] 
0.2 
3.1 
0.2 
0.4 
0.7 
0.5 
D  6 
0.4 
0.6 
0.4 
0.5 
2.2 
8.4 
0.3 
3.6 
0.9 

a  2 

1.8 
5.9 
0.5 
3.3 
2.2 
2.4 
12 
4.6 
4.2 
2.7 
5.0 
3.9 
9.2 
3.0 
5.0 
1.9 
1.8 

-O 
0.3 
3.5 
0.1 
0.4 

'6"2 
0.3 
5.2 
2.7 
11.3 
18.5 
7.1, 
7.6i 
6.1 
29.0 
1.2 
0,6 

7.  -2 
5^5 
3-2.6 
1.7 
9.1 
6.6 
8.1 
4.4 
16.4 
13.0 
17.5 
16.4 
14.7 
7.6 
14.1 
11.8 
8.8! 
7.9! 

Rice,  with  husk  

kk     husked           . 

Millet,  with  husk  
"      husked  

Sorghum 

1.2 

"c  t 

0.4 
5.7 
1.7 
0.9 
1.0 
0.2 
4.0 
02 
0  4 

'6!2 

0.1 

"r!i 

2.3 
0.2 
4.6 

'j>"5 
0  6 
0  2, 

's'a 

1.7 

io'i 

0.8 
7.8 
2.7 
2  4 

Buckwheat  

Rape      seed... 

Flax         "    

Hemp       ** 

Poppy       "*• 

Mustard   "    

Beet         "     

Turnip     " 

Carrot       "     

Peas  .  .  .  .  

Vetches  .. 

384  HOW   CROPS   GROW. 

COMPOSITION  OF  FRESH  OR  AIR  DRY  AGRICULTURAL  PRODUCTS. 


£fubstance. 

| 

. 

j' 

1 

Magnesia  . 

1 

^•8 

P 

| 

j 

X.— GRAINS  AND  SEEDS  OF  AGRICULTURAL  PLANTS. 

11.61   1.51    0.41 


Field  beans  

1411   29.6  12  0 

041   20     15 

Garden  beans 

148J   20  1  11  5 

0  8J    2  0    2  0 

Lentils 

134;   178    77 

18    04!   09 

Lupines  

138'   84.011.4 

6*0    2'li    27 

Clover  seed. 

l.V)     36  ')  1.'!  s 

02l   45'    23 

Esnarsette  seed.  .  . 

IfiOl   37.6  10.8 

1.1     2.5  11.9 

7.8 

6.3 

s.l 
I-.1.! 

'.HI 


1.0  0.2  0.32.5 

...  0.2  0.6|.  . 

2.3  0.3  0.6!.. . 

1.7  0.9|  0.5'... 

1.2  0.3]  0.4J2.8 


XL— FRUITS  AND  SEEDS  OF  TREES,  ETC. 


Grape  seeds 

Alder       "     

Beech  nuts 

Acorns,  fresh 

"       dried 

Horse-chestnuts,  fresh. 


Apple,  entire  frui 
Pear,         " 
Cherry,      " 
Plum, 


huak. . 


1201    24.7 
140    44.2 

7.1 

16.6 

180 

27.1 

6.2 

i)  6 

6.2 

ir.s 

18.3 

11.8 

in.' 

12.0 

7.1 

318 

8.0 

6.1 

840 

2.7 

1.0 

800 

4.1 

2.2 

rso 

4.3 

2.2 

820 

4.0 

2.4 

XlLc-LEAVES  OF 


2.1 

8.4 

o.i 

3.5 

13.6 

2.7 

3.1 

6.7 

0.1 

0'.5 

0.7 

0.1 

1.0 

1.3 

0.1 

1.4 

0.1 

0.8 

o'.: 

0.2 

0.1 

0.4 

0.2 

0.3 

0.1 

0.2 

0.3 

0.2 

0.4 

TREES. 

5-21 


ir. 


0.5 


'I  V.  A 

0.4  0.2 

0.6  0.2 

0.7  0.2 

0.61  0.2 


0.8 

0.1 

... 

l.l 

0.6 

o'.i 

... 

O.S 

0.1 

(i,! 

0.3 

0.8 

0.1 

0.4 

0.1 

.. 

0.1 

0,1 

o'.i 

.. 

0.1 

... 

... 

Mulberry  .....................  16701    11 

Horse-chestnut,  spring  ........  700     21.5 

autumn  ......  600| 

Wainut,  sprinjr  ..............  700 

"       autumn  ............    600 

Beech,  summer  ........   ......  750 

"       autumn  _____  ..........  660 

Oak,  summer  .................  1700 

"     autumn 
Fir,  autumn 
Red  pine,  autumn 


2.8 


30.1! 
23.  2! 
28.4 
12.1 
30.5  ! 
18.8 


6.9 

9.9 

7.6|  ... 
2.2  0.2 
1.6|  0.2 


3.0 
4.6 

12.21 
6.2; 

15.3i 
4.4 

18.1 
8.6 
'.i.:. 
8.6 
•l.o 


1J 

0.1 

4.1 

5.0 

1.3 

0.6    0.8 

8.6 

0.5 

4.2|  1-2 

4.9 

0.6 

0.3 

0.1 

l.l 

0.8 

0.6 

0.2 

o  '.i 

0.4 

1.8 

0.1 

1.8 

1.1 

10.3 

0.1 

1.1 

0.4 

0.6 

l.fl 

0.9 

6.1 

1.3 

0.3 

0.8 

0'.3 

2.1|  0.7 

18.4 

XIII.— WOOD.      (AlR-DRY.) 


Mulberry                    

160 
160 
160 
L60 
160 
(60 
160 

160 
160 

13.7 
2.6 
5.5 
8.9 
12.3 
5.1 
10.2 

28.1 
25  5 

0.9 
0.3 
0.9 
1.4 
1.7 
0.5 
2.0 

5.5 
39 

2.0 
0.2 
0.2 
0.2 
0.3 
0.2 

Birch  

Bec'ch,  body-wood  

"      small  wood  

"      brush  

Oak,  body-wood        

"    small  branches  with  bark 
Horse-chestnut,  young  wood 
in  autumn                    

Walnut 

Apple  tree  

L60 
160 
160 
160 
160 

11.0 
2.1 
2.4 
2.8 
8,7 

1.3 
0.1 
0.4 
0.3 
0.4 

0.2 
0.6 
0.2 
0.1 
0.2 

Jiinl  pine            

White  nine 

Fir                

Larch.  .  . 

L.6 

8.7 

3.0 

0.6 

0.2 

0.2 

0.8 

7.8 

0.3 

1.4 

0.5 

0.6 

O.S 

1.5 

0.2 

0.1 

0.6 

3.1 

0.3 

o.i 

0.3 

1.8 

4.1 

1.0 

0.1 

0.6 

1.8 

5.9 

1.5 

0.1 

1.2 

o.a 

3.7 

0.3 

0.1 

0.1 

0.8 

5.5 

0.9 

0.2 

0.3 

... 

1.5 

14.3 

5.9 

0.2 

0.4 

10 

14.2 

3.1 

0.8 

0.7 

0.1 

0.6 

7.8 

0.5 

0.3 

0.2 

0.1 

1.0 

0.1 

0.1 

0.1 

O.i 

1  ° 

0.1 

0.1 

ii.-.' 

o!a 

1.8 

o.- 

0.1    0.4 

0.7 

0.7 

O.l 

O.ll   0.1 

... 

XIV.-BARK. 


Birch                                

160 

!  -•  1 

160 
160 

i  61  1 
160 

11.3 
65.8 
64.4 
88.8 

88.1 
17.1 

0.4 
18.5 

1.3 
2.3 
0.5 

0.6 

i'.o 

n.'.i 
0.2 

<1.9     5.2     O.R 
•J.-J  ::• 
88.1    3.2 
1.114.8    ().«i 
0.819.6    0.7 
0.2l   7.51    1.4 

0.2 
0.6 
0.1 
0.2 
0.5 
0.1 

2.3 

0.6 

0,1 

8,8 

2.3 
5.8 

0.2 
0.7 
0.2 
0.1 

°:8I 

Horse-chestnut,  yonn^  in  :mt. 
V.'alnut.                      "         "     " 
Ri  d  pine 

Fir... 

APPENDIX. 


385 


TABLE    IIL 

PBOXIMATB  COMPOSITION  OP  AGRICULTURAL  PLA.NTS  AND  PRODUCTS, 
giving  the  average  quantities  of  Water,  Organic  Matter,  Ash,  Album 
inoids,  Carbohydrates,  etc.,  Crude  Fiber,  Fat,  etc.,  by  Professors 
WOLFF  and  KNOP.* 


Substance. 


Meadow  hay,  medium  quality. 
Aftermath  .................. 

Red  clover,  full  blossom  ...... 


HAY. 


ripe 
,  full 


White  clover,  full  blossom 

Swedish  or  Alsike  clover  (Trifolium  hybridum)  16. 

"       clover,  ripe. 
Lucern,  young 


in  blossom. 


Sand  lucern  early  blossom  (Medicago  intermedia)  16 

Esparsette,  m  blossom " 

Incarnate  clover,  do       (Trifolium  incarnaturri). 

Yellow         "       do       (Medicago  lupulina) 

Vetches,  in  blossom 

Peas,        "       "        , 

Field  spurry,  in  blossom  (Spergula  arvensis) 

"          "      after  blossom...   

Berradella,         " 
before 

Italian  Rye  grass  (Lolium  italicum)  

Timothy  (Pnleum  pratense) 

Early  meadow  grass  (Poa  annua) 

Crested  dog's  tail  (Cynosurus  cristatus) 

Soft  brome  grass  (Bromus  mottis) 


(Ornithopus  sativus). 


Orchard  grass  (Dactylis  glomerata).. 
Barley  grass  (Ho    ' 


,  Jordeum  pratense) 

Meadow  foxtail  (Alopecurus  pratensis) 

Oat  grass,  French  rye  grass  (Arrhenatherum 

avenaceum) 

English  rye  grass  (Lolium  perenne) 

Harter  Schwingel  (Festuca  ?) 

Sweet-scented  vernal  grass  (Anthoxanthum 

odoratum) 

Velvet  grass  (Holcus  lanatus).. 

Spear   grass,    Kentucky    Blue   grass    (Poa 

pratensis) 

Rough  meadow  grass  (Poa  trimalis) 
Yellow  oat  grass  (Avena-flan 
Quaking  grass  (Briza  media) 
Average  of  all  the  grasses. . 


14  3 

79.2 

6.5 

9  5145  7  24  0 

1Q.1 

6.213.4 

29.935.8 

16.7 

77^7 

5  6 

9.4 

20  3  4S  0 

16.7 

74.8 

8.5 

14.934.325.6 

16.7 

75.0 

8.3 

16.7 
16.7 
16.7 
16.7 

78.3 
74.6 
76.9 

77.2 

5.010.2 
8.719.7 
6.414.4 
6.115.2 

i  23.  1(45.0 
32.9  22.0 
22.540.0 
26.9J35.1 

16  7 

77  1 

6  2 

13.3 

3H.727.1 

16.7 

76.1 

7.2il2.2|30.i 

33.8 

16.7 

77.3 

6.0 

14.636.526.2 

16.7 

75  0 

8.3 

14.235.3'25.5 

16.7 

76.3 

7  0 

14  ftflfl  825  2 

16.7 

73.8 

9.5ll2.6l39.822.6 

16  7 

75  5 

7.8 

7.841.726.0 

16.7 

77.7 

16.7 

75  8 

7^5 

15!337!226!l 

14.3 

77.9 

7.8 

8.751.416.9 

14.381.2 

4.5 

9.7 

48.8 

22.7 

14.383.3 

2.410.1 

47.225.9 

14.380.2 

5.5 

9.548.022.6 

14.380.7 

5.0 

14.835.031.0 

14.3 

81.1 

4.611.640.7J28.9 

14.3 
14.3 

80.4 
79.0 

5.3 
6.7 

9.642.0 
10.639.5 

27.2 
29.0 

14.3 

75.8 

9.9 

11.1 

35.3 

29.4 

14.379.2 

6.510.238.9 

30.2 

14.381.0i  4.7 

10.4 

37.5 

33.2 

14.3SO.3l  5.4 

8.940.2 

31.2 

14.  380.  2;  5.5 

9.9:36.7 

33.6 

14.3!80.6   5.1 

8.9!39.1 

32.6 

14.378.6!  7.1 

8.4i37.6 

3-2.6 

14.379.81  5.9 

6.4142.630.8 

14.373.3j  7.4 

5.2I42.8J30.3 

14.3!79.9  -5.8 

9.5i41.7'28.7 

2.0 
2.4 
3.2 
2.0 
3.5 
3.3 
2.2 
3.3 
2.5 
3.0 
2.5 
3.0 
3.3 
2.5 
2.6 
3.2 
2.6 
1.5 
1.9 
2.8 
3.0 
2.9 
2.8 
1.8 
2.7 
2.0 
2.5 

2.7 
2.7 
2.0 


3.1 


2.G 


*  Landwirtfischaftticher  Kalender,  1867,  through  Knop's  Agricultur-  Chemle, 
1868,  pp.  715-720.  This  Table  is,  as  regards  water  and  ash,  a  repetition  of  Table 
II,  but  includes  the  newer  analyses  of  1865-7.  Therefore  the  averages  of  water 
and  ash  do  not  in  all  cases  agree  with  those  of  the  former  Tables.  It  gives  be 
sides,  the  proportions  of  nitrogenous  and  non-nitrogenous  compounds,  i.  e.,  Al 
buminoids  and  Carbohydrates,  etc.  It  also  states  the  averages  of  Crude  fiber  and 
of  Fat,  etc.  The  discussion  of  the  data  of  this  Table  belongs  to  the  subjects  of 
Food  and  Cattle-Feeding.  They  are,  however,  inserted  here,  as  it  is  believed 
they  are  not  to  be  found  elsewhere  in  the  English  language.  —  t  Organic  matter 
here  signifies  the  combustible  part  of  the  plant.— ]  Carbohydrates,  etc.,  includes 
fat,  starch,  sugar,  pectin,  etc.,  all  in  fact  of  Org.  matter,  except  Albuminoids  and 
Crude  fiber.— $  Crude  fiber  is  impure  cellulose  obtained  by  the  processes  describ 
ed  on  pages  60  and  61.— 1  Fat,  etc.,  is  the  ether-extract  p.  SH,  and  contains  be» 
sides  fat,  wax,  chlorophyll,  and  in  some  cases  resins. 
H 


HOW   CHOPS   GROW. 


PROXIMATE  COMPOSITION  OP  AGRICULTURAL  PLANTS  AND  PRODUCTS. 


Substance. 


STRAW. 


Winter  wheat 

Winter  rye 

Winter  Bpelt.. 
Winter  barley 
Summer  barley 


Oat 

Vetch  fodder. 
Pea... 


with  clover. 


Lentil... 
Lupine... 
Maize... 


14.3180.2 
14.382.5 
14.379.7 
14.380.2 
14.378.7 
14.377.7 
14.3]80.7 
14.379.7 
14.381.7 
17.377.7 
14.379.2 
14.281.4 
14.0)82.0 


5.5  2.0,30.248.0!  1  5 

3.2  1.5;27.0!54.0j  1  8 

6.0  2.0  27.750.5i  1  4 

5.5  2.029.848.4!  1.4 


7.0  3.0,32.743.0 
8.0  6.034.737.5 
5.0  2.538.240.0 
6.0;  7.5:28.244.0 
4.0  6.535.240.0 
5.010.2|33.534.0 
6.5^14.027.236.6 
4.4|  4.934.741.8 
4.0!  3.0|39. 040.0 


CHAFF  AND  HULLS. 


Wheat 

Spelt 

Kye 

Barley 

Oat 

Vetch 

Pea 

Bean 

Lupine 

Rape 

Maize  cobs.. 


Grass, 


15.0|77.0 
14.3179.7 
15.077.0 
14.3!82.9 
10.377.5 
10.3J83.2 


GREEN  FODDER. 

75.0  22.9 
.029.0 
83.015.5 


14.3173.712.0 
14. 3|77.2 
14.3178.2 


14.372.7 


14. 3167.718.0 


T.r, 

13.0 


8.0 
i.O 


4.5133. 2|36.0 
2.932.841.5 
3.528.2146.5 
3.038.7:30.0 
4.029.7i34.0 
8.532.5:3(5.0 
M36.6i35.0 


8.010.529.5|37.0 


2.547.2.33.0 
3.540.0:34.0 
1.444.0|37.8 


before  blossom . . 

after          " 
Red  clover,  before      " 

full  "        78.020.3 

White    "      "  "        80.517.5 

Swedish  clover,  early  blossom 85.013.5 

full  " 82.016.2 

Lucern,  very  young 81.017.3 

"       in  blossom 74.0  24.0 

Sand  lucern,  early  blossom 78.020.1 

Esparsette,  in  "        [(urn)  80.9jl8.5 

Incarnate  clover  in      "       (Trifdium    incarna- 


Yellow  clover,  in  blossom  (Medicago  litpulina) . 


Serradella, 

Vetches, 

Peas,  " 

Oats,  early  blossom 

Rye.. 


(OrnWiopus  sativus). 


Maize,  late  end  August 


early  " 


Hiiiiirnrian  millet,  in  blossom  (Panicwn  germani- 
Sorcihum  saccharatitm 
Sorghum  vulgare. . 
Field  epurry  in  blc 

Cabbage , 

stumps 


in  blossom. 


Field  beet  leaves 90.5 


Carrot  leaves. 

Poplar  and  elm  leaves. 

Artichoke  stem 

Rape  leaven 


81. 5116. S 

80. Oil8. 5 
80.0H8.7 
82.0ll6.'2 
81.8  17.0 
81.017.6 


......  84.S14.6 

[euro)  82.,'  if,. 7 


i  ;.-,. i ;  :•.•>.<) 
74.095.1 
77.321.6 
80.018.0 
9.8 
82.0  16.1 
6.7 
14.2 


8-2.2 


70.028.0 
80.017.3 


L.a 


3.3 
.7  3.7 
.0  3.5 


•{.(I 


I.I 
1.9 
1.8 
8.6 

2.1) 

.7 


Ury75.524.520.0!47.5 


3.012.9 


2.1    

2.0    2.515.0 

1 

1 

2 

1.5   3.3 

1 

1 

'2 

1 

1 


7.0 
11.5 


6.6 


4.B 


6.5 

7..'! 
....  ...    5.0 

I.l|l0.9  4.7 
5.9il5.0|ll  5 
I.5J15.JU  7  3 
2. 911. 9  6  7 
2.3;10.4  5.3 

J.O 


«.U.  J 

1.5 

1.1 
l.'.l 


12.2 
4.6 

_  _  8.0 
6.015.5 
3.3ll0.6 


ti.5 


1.4 
1.7 
2.0 
2.0 
2.0 
1.0 
2.0 
1.5 
1.1 


1.4 
1.3 
1.2 
1.5 
1.5 
2.0 
2.0 
2.0 
2.5 
1.6 
1.4 


0.8 
0.7 
0.7 
0.8 
0.8 
0.6 
0.6 
0.6 
0.7 
0.8 
0.6 
0.6 
0.8 
0.4 
0  6 
0.6 
0  B 
0.9 
0.5 
0.5 
1.5 
1.4 
? 

0.7 
0.4 
0.8 
0.5 
1.0 
1.5 
0.8 
2.0 


APPENDIX. 


PROXIMATE  COMPOSITION  OF  AGRICULTURAL  PLANTS  AND  PRODUCTS. 


Substance. 

I 

Organic 

\Mdtter. 

-. 
1 

X  «- 

tj 

!* 

'*  * 
1 

ROOTS  AND  TUBERS. 

,Potato 95. OJ24. 1| 

Jerusalem  Artichoke 80.0|18.9 

Turnip  Chervil?  (Koerbelriibe) 76.0;23.1 

Kohl-rabi 88.0,10.8 

Field  beets  (about  3  Ibs.  weight) 88.0  11 . 1 

Su<:ar  beets  (1-2  Ibs.) 81.517.7 

Ruta-bagas  (about  3  Ibs.) 87.012.0 

Cai-rot  (about  ft  Ib.) 86.014.0 

Giant  carrot  (1-2  Ibs.) 87.0  12.2 

Turnips  (Stoppelriibe) 91.5   7.7 

Turnips  (Turmpsriibe) 92.0   7.2 

Parsnip 88.311.0 

Pumpkin 94.5   4.5 

GRAINS  AND  SEEDS. 

Rice 14.6184.9 

Winter  wheat 14.4J83.6 

Wheat  flour 12.686.7 

Spelt ..  14.881.3 

Winter  rye 14.383.7 

Rye  flour 14.084.4 

Winter  barley 14.383.4 

Summer  barley 14.3)83.1 

Oats 14.3182.7 

Maize .  14.483.5 

Millet 14.083.0 

Buckwheat 14.083.6 

Vetches 14.383.4 

Peas 14.3:83.2 

Beans  (field) 14.5  S3. 0 

Lentils 14.5,825 

Lupines    ..  14.5182.0 

Acorns  without  shell,  dry 20.078.4 

"     with         "      fresh 56.0*3.0 

Chestnuts  without  shell,  fresh 49.2  49.0 

Madia  seed 8.486.9 

Flax  seed 12.382.7 

Rape  seed 11.086.1 

Hemp  seed 12.283.6 

Poppy  seed 14.7J78.3 

Horse  chestnut 


0.9 
1.1 
0.9 
1.9 

0.9 

o.s 

1.0 
1.0 

o.s 
0.8 
0.8 
0.7 
1.0 


8.015.6] 

3.217.0; 
7.3 
9.1 


•2.'.', 
1.1 
1.015.4 
1.6  9.3 
1.510.8 


.1 

0.3 

.y 

.0 

ti 

.-2 

0.2 

).<) 

0.1 

8 

0.1 

.1 

0.1 

.7 

0.2 

.'2 

0.2 

.0 

0.1 

.0 

0.1 

.0 

o.a 

1.0 

0.1 

0.-5I  7.5176.5 

2.o!l3.0'67.6 

0.7111. 8174.1 

3.9110.054. 

2.0|ll.069.2 

1.610.5172.5 

2.3    9.0165.9 


s  K; 


2.6   9.666.6 

3.012.060. 
2.1110. 0168.0 
3. OJ14. 5:62.1 
2.4 


SI  10 


.059.615.0    2.5 
2.327.5J49.2 
2.5:22.4:52.3 
3.5!25.5|45. 
3.0123.8)52.0 
3.534.533.014. 
5.068.8 


2.0i36.5 


3.0145.2 
4.722.9146. 
5.0!20.5|55.0 
3.9|19.4!55.4 
4.216.355. 
7.0I17.5J54.7 
1.210.5158.3 


0.9:  0.5 
3.0    1.5 

0.7  1.2 
.51  1.5 
3.5  2.0 


1.6 
2.5 
2.5 
6.0 
7.0 
1.0 


5  11 


•2.7 
2.5 
2.0 
2.6 
.0 


4.3 
2.3 
2.5 


018 


„. 041.0 
7.237.0 
10.3140.0 
2.133.6 
6.1:41.0 
4.02.30 


212 


REFUSE. 

beet  cake [chine  70 .0  26 . 6 

"        "    residue  from  centrifugal  ma-  82.0  16.8 


Potato  slump 

Rye  slump 

Maize  slump 

Molasses  slump 

Brewer's  grains 

Malt  sprouts 

Fresh  malt  with  sprouts . . 
Dry  malt  without  sprouts. 

Wheat  bran 

Rye  bran 

Rape  cake 

Linseed  cake 

Gold  of  pleasure  cake 


maceration.... 


6  6.6 
94.8  4.6 
89.010.5 
89.010.5 
92.0  6.3 
76.6  22.2 

8.085.2 
47.550.8 

4.2193.1 
13.181.8 
12.5;s3.0j 
15.0J77.6 
11.5180.6! 
15.0178.1, 


1.8 


818.5 

012.2 

4.4 


14 
4.5J14 
7.428 
7  928 
6  928 


4.911.1 


6.823.044.717.5 


6.539.5 
8.876.3 


6.2 


050.017.8 
553.515.0 
3J33.5;15. 
3141.311.. 
5)37.1  12.5 


0.2 
0.1 
0.1 
0.1 
0.4 
1.2 


1.6 
2.5 
1.5 
2.5 
3.8 
3.5 


010.0 
80 


388 


HOW   CROPS   GROW. 


PROXIMATE  COMPOSITION  OF  AGRICULTURAL  PLANTS  AND  PRODUCT* 


Substance. 


REFUSE. 

Poppy  cake 

Hemp  cake 

Beechnut  cake 

"    without  shells 

Beet  molasses 

Potato  fiber. . .  


10.0181.6 
10.585.5 
10.084.8 


12.579.8 


12.5 

16.71 


82.6J17.1 


72.5  10.8 


.432.537.711.4 
4.027.036.522.0 
5.224.031.320.5 
5.5 

i'.s 


7.737.3:36.9 


8.064.5 
0.815.0 


8  J 
6.5 

7.5 


COFFEE.    TEA. 


Coffee  bean 

Chocolate  bean.. 
Black  China  tea. 
Green  "  "  . 


7.0  IQ.0'49. 0134. 0112.4 
4.020.052.013.044.0 
6.0  5.032.040.0  2.0 
6.0  5.027.045.0  2.0 


TABLE    IV. 


DETAILED  ANALYSES  OF  BREAD  GRAINS. 


Analyst. 


WHEAT. 


PromElsaes 

44  Saxony...... 

k*    America 

44    Flanders 

44    Odessa 

44  Tanganrock. . 

"    Poland 

44    Hungary 

44    Egypt 


14.659.7 
11.864.4 
10.963.4 
10.761.0 
14.359.6 
13.6  57.9 
21.553.4 
13.4  62.2 
20.655.4 


7.211.2 
1.42.6 
3.81.2 
9.21.0 
6.31.5 
7.91.9 
6.81.5 
5.41.1 


Prom  Hessia. , 
44  France.. 
14  Saxony. 


6.01.1 
RYE. 
13.6150.6 
11.656.510.21. 
9.164.9 
9.6|56.7 


1.7 
2.5 
8.3 
1.8 
1.7 
2.3 
1.7 
1.7 
1.8 


.6ll4.0!Boussinganlt. 

.6  15.6;Wunder. 

.6110.8' Poison, 

.714.6Peligot 

.415.2       " 

.614.8 

.913.2 
1.714.5 
1.614.8 


Prom  Salzmiinde,  Prussia 


10.550.3 
13.253.7 
9.360.4 


0.42. 
6. 4J2.1 
BARLEY. 
5.52. 
4.22.6 
1.22. 
OATS. 


1.8115.0 
2.214.1 

1.418.3 
3.3|16.5 

Fresenius. 
Payen. 
A.  Miiller. 
Wolff. 

3.8'15. 

.8  12.0 
2.4 


7  Wolff. 
Poison. 


15.0  Grouven. 


•om  Vienna  

8.8155.4 
15.732.2 
10.2|  

...  |6  i 

9.6 

io!6 

AT. 
1.0 
1.8 
8.5 

12.7 
4.1 
|2.7 

2'.  5 
2.0 

2.4 

14.6  A.  Miiller. 
12.9  Krocker. 
12.6  Anderson. 

12.7|Bibra. 
13.7      " 
13.0  Bouasingault. 
14.2  Horsford  &  Krocket 
14.0Zenneck. 

BU< 

2.6178.9 
3.676.7 
13.1  .... 

JKWHE 
3.810.9 
4.31.3 

....3.9 

8.537.8 

9.145.0 

7.i'6.4 

22.0 

Untiueked 


Prom  Saxony 

44    America 

"    Galacz. 

14    Switzerland 


MAIZE. 


4.9 
15.  £ 


12.5 


3.2|10.5|HellriegeL 

1.7  12.0  Poison. 
1.811.8       " 
..  lO.GBibr*. 


APPENDIX.  889 

DETAILED  ANALYSES  OP  BREAD  GRAINS. 


Analyst. 


From  Piemont 

44     Patna 

44     Piemont 

44     East  Indies 


7.5 

7.279.9 

7.8 


5.9  73.9 


....  0.5 
1.60.1 
....  0.2 
2.30.9 


0.9 
0.5 
3.4 
2.0 


0.5114.6  Boussinganlt 
0.9   9.8  Poison. 
0.3  13.7  Pehgot. 
..  14.0Bibra. 


MILLET. 

Husked.   Hagenan i20.6 13.0 

44      Nuremberg |10.357.0  11.0|8.0 


2.4   2.2|14.0!Boussingault 
2.0    ...  12.2Bibra. 


TABLE    V. 

DETAILED  ANALYSES  OF  POTATOES,  by  GROUVEN. 
(Agricultur-Chemie,  Zte  Auf.,  pp.  495  &  355.) 


White  Potatoes,  newly  dug, 

Various  Sorts.  Aver 
age  of  19  Analyse*. 

unmanured. 

manured. 

Water  

74.95 
0.471 

&[•** 

1.31J 
0.76 
2.00 
0.07 
17.33 
1.90 
0.88 

78.01 
0.891 

£8U» 

2.02J 
1.56 
1.50 
0.05 
13.40 
1.24 
1.05 

76.00 
2.80 

1.81 

0.30 
15.24 
1.01 
0.95 

Albumin  .            . 

Casein  

Gliadin  &  Mncidin  (?)  

Veg  Fibrin 

Gum  and  pectin  

Org.  Acids    

Pat 

Starch  

Cellulose    

Ash 

100. 

100. 

TABLE    VL 

DETAILED  ANALYSES  OF  SUGAR  BEETS. 


1 

^1 

| 

Org.  Acids 
pectin,  &c. 

14 

1 

Analyst. 

Hohenheim 

81.5 
84.1 

81.7 
79.5 
80.0 

80.0 
79.9 
82.7 
81.8 
82.1 
82.5 
84.  4 
82.7 
84.1 

0.87 
0.82 
0.84 
0.90 
0.70 

0.68 
0.65 
0.93 
1.16 
1.14 
1.05 
1.14 
1.42 
1.20 

11.90 
9.10 
11.21 
12.07 
12.90 

13.37 
13.32 
12.34 
10.15 
9.25 
8.45 
9.80 
11.57 
9.82 

3.47 
3.90 
3.86 
5.09 
5.00 
»  1 
5.' 
5.5 
3.' 
5.' 
6., 
T-i 
3. 
8.< 
4.( 

i.as 

1.05 
1.36 
1.52 
1.20 

„•—  ^ 

n 

53 
24 

r7 
« 

)7 
)6 
i3 

HI 

0.89 
0.99 
0.94 
0.88 
0.70 

0.74 
0.60 
0.79 
1.12 
1.15 
0.93 
0.69 
0.68 
0.77 

Wolff. 
Ritthansen. 

it 
Grouven. 

Stockhardt 
tt 

M 

Bretschiieidw. 

Moeckern  

44        2   Ibe. 

"        yz    "  

Bickendorf,  1V£  Ibs  

Slanstsidt,  2   Ibe  

Lockwitz,  1  14  Ibs. 

Tharand,   I1/,  "  manured... 

44         3}4  "         " 

4      «                  

Silesia,  nnmanured  

44      manured  with  nitrate  of  soda 
14    man'd  with  phosphate  of  lime 

Average. 

81.5 

0.9o'  11.  5!  8.7 

1.8 

0.85 

890 


HOW   CROPS   GROW. 


21 


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301 


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APPENDIX. 


TABLE    VIII. 

FRUITS  ARRANGED  IN  PHE  ORDER  OP  THEIR  CONTENT  OP  SUGAR, 

(average,)  FRESENIUS. 


percent. 

Peaches 1.6 

Apricots 1.8 

Plums 2.1 

Reineclaudes 3.1 

Mirabelles 3.6 

Raspberries 4.0 

Blackberries 4.4 

Strawberries ...5.7 

Whortleberries 6.8 


percent. 

Currants 6.1 

Prunes 6.8 

Gooseberries 7.2 

Red  pears 7.5 

Apples 8.4 

Sour  cherries .  8.8 

Mulberries 9.2 

Sweet  cherries 10.8 

Grapes 14.9 


TABLE    IX. 

FRUITS  ARRANGED  IN  THE  ORDER  OF  THEIR  CONTENT  OF  FREE 
ACID  EXPRESSED  AS  HYDRATE  OF  MALIC  ACID,  (average,)  FBESENIUS. 


percent. 

Red  pears 0.1 

Mirabelles 0.6 

Sweet  cherries 0.6 

Peaches 0.7 

Grapes 0.7 

Apples 0.8 

Prunes 0.9 

Reineclaudes 0.9 

Apricots 1.1 


percent. 

Blackberries 1.2 

Sour  cherries 1.3 

Plums 1.8 

Whortleberries 1.3 

Strawberries 1.8 

Gooseberries 1.5 

Raspberries   1.5 

Mulberries 1.9 

Currants, 2.0 


TABLE    X. 

FRUITS   ARRANGED   ACCORDING   TO  THE   PROPORTIONS  BETWEEN 
ACID,  SUGAR,  PECTIN  AND  GUM,  ETC.,  (averages,)  FRESENIUS. 


Add. 

Sugar. 

Pectin,  &um,  etc. 

Plums 

1  6 

8  1 

1.7 

6.4 

Peaches  

2.3 

11.9 

Raspberries  .                     .... 

27 

1  0 

Currants  

3.0 

0.1 

Reineclaudes  

8.4 

11.8 

Blackberries            

3.7 

1  * 

Whortleberries 

43 

•»  4 

Strawberries  

4.4 

0.1 

Gooseberries  

4.9 

0.8 

Mulberries  

4.9 

1.1 

Mirabelles  

62 

9.9 

Sour  cherries  

69 

1.4 

Prunes                  .          . 

70 

4  4 

11.2 

5.6 

Sweet  cherries  

17.3 

2.8 

Grapes               

20.2 

8  0 

Red  pears 

946 

44  4 

17* 

394 


HOTV  CROPS   GROW. 


TABLE    XL 

FBUTTS  ARRANGED  ACCORDING  TO  THE  PROPORTIONS  BETWEEN 
WATER,  SOLUBLE  MATTERS  AND  INSOLUBLE  MATTERS, 

(averages,)  FRESENITTS. 


Water. 

SolubleMatters. 

Insoluble  Matters. 

Raspberries  

100 

9.1 

6.9 

Blackberries                    . 

100 

9  3 

6.5 

Strawberries  

100 

9.4 

5.2 

Plums 

100 

9  7 

0.9 

Currants  

100 

11.0 

6.6 

Whortleberries  

100 

12.1 

18.9 

Gooseberries 

100 

12  2 

3.6 

Mirabelles         

100 

13.0 

1.5 

Apricots                            . 

100 

13  3 

2.1 

Red  pears  

100 

14.3 

5.5 

Peaches               ...          

100 

14.6 

2.1 

100 

15.3 

3.2 

Sour  cherries        

100 

16.5 

1.3 

100 

16  6 

1.5 

Apples                     

100 

16.9 

3.6 

Reineclandes 

100 

18.5 

1.2 

Cherries      

100 

18.6 

1.5 

Graoes... 

100 

22.8 

5.8 

TABLE    XH. 

PROPORTION  OF  OIL  EN  VARIOUS  AIR-DRY  SEEDS,  according  to  DERJOT. 

(Knap's  AgriciMur  Chemie,  p.  725.) 
(The  air-dry  seeds  contain  10-12  per  cent  of  hygroscopic  water.) 

Colza,  common 40-45 

"       Schirmraps 44 

"       redlndia 40 

"  white  •*  40 

Flax 34 

Poppy 40-50 

Sesame 53 

Mustard,  white 30 

•*  black 29 

Hemp 28 

Peanut: 88 


Gold  of  Pleasure 

Watermelon 86 

Charlock 15-42 

Orange 40 

Colocynth 

Cherry 43 

Almond 40 

Potato 

Buckthorn 

Currant *» 

Beechnut * 


JU 


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